Top 100 C++ Coding Interview Questions and Answers (2024)
Last Updated :
11 Jan, 2024
C++ is one of the most popular languages in the software industry for developing software ranging from operating systems, and DBMS to games. That is why it is also popular to be asked to write C++ Programs in live coding sessions in job placement interviews.
This article provides a list of C++ coding interview questions for beginners as well as experienced professionals. The questions are designed to test candidates’ understanding of the following topics:
- C++ syntax and semantics
- Data structures and algorithms
- Object-oriented programming
- Memory management
- Pointers
- Templates
List of 100 C++ Coding Interview Questions and Answers
Here is a list of 100 C++ coding interview questions and answers
1. Write a C++ Program to Check Whether a Number is a Positive or Negative Number.
C++
#include <iostream>
using namespace std;
int main()
{
int number;
number = -100;
if (number >= 0) {
cout << number << " is a positive number." << endl;
}
else {
cout << number << " is a negative number." << endl;
}
return 0;
}
|
Output
-100 is a negative number.
2. Write a Program to Find the Greatest of the Three Numbers.
C++
#include <iostream>
using namespace std;
int main()
{
int a = 10, b = 20, c = 30;
cout << "The Greatest Among Three Numbers is : ";
if (a >= b && a >= c) {
cout << a << endl;
}
else if (b >= a && b >= c) {
cout << b << endl;
}
else {
cout << c << endl;
}
return 0;
}
|
Output
The Greatest Among Three Numbers is : 30
3. C++ Program To Check Whether Number is Even Or Odd
C++
#include <iostream>
using namespace std;
bool isEven(int n) { return (n % 2 == 0); }
int main()
{
int n = 247;
if (isEven(n) == true) {
cout << "Even" << endl;
}
else {
cout << "Odd";
}
return 0;
}
|
For more information, refer to the article – C++ Program To Check Whether Number is Even Or Odd
4. Write a Program to Find the ASCII Value of a Character
C++
#include <iostream>
using namespace std;
int main()
{
char ch;
ch = 'A';
cout << "The ASCII value of " << ch << " is " << int(ch)
<< endl;
return 0;
}
|
Output
The ASCII value of A is 65
5. Write a Program to Check Whether a Character is a Vowel or Consonant
C++
#include <cctype>
#include <iostream>
using namespace std;
int main()
{
char ch = 'e';
if (isalpha(ch)) {
if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o'
|| ch == 'u' || ch == 'A' || ch == 'E'
|| ch == 'I' || ch == 'O' || ch == 'U') {
cout << ch << " is a vowel." << endl;
}
else {
cout << ch << " is a consonant." << endl;
}
}
else {
cout << ch << " is not an alphabet." << endl;
}
return 0;
}
|
6. Write a Program to Print Check Whether a Character is an Alphabet or Not
C++
#include <cctype>
#include <iostream>
using namespace std;
int main()
{
char ch;
ch = 'a';
if (isalpha(ch)) {
cout << ch << " is an alphabet." << endl;
}
else {
cout << ch << " is not an alphabet." << endl;
}
return 0;
}
|
7. Write a Program to Find the Length of the String Without using strlen() Function
C++
#include <cstring>
#include <iostream>
using namespace std;
int main()
{
string str = "GeeksforGeeks";
int length = 0;
for (int i = 0; str[i] != '\0'; i++) {
length++;
}
cout << "The length of the string is: " << length
<< endl;
return 0;
}
|
Output
The length of the string is: 13
8. Write a Program to Toggle Each Character in a String
C++
#include <cstring>
#include <iostream>
using namespace std;
int main()
{
string str = "GeeksforGeeks";
for (int i = 0; str[i] != '\0'; i++) {
if (islower(str[i])) {
str[i] = toupper(str[i]);
}
else if (isupper(str[i])) {
str[i] = tolower(str[i]);
}
}
cout << "Toggled string: " << str << endl;
return 0;
}
|
Output
Toggled string: gEEKSFORgEEKS
9. Write a Program to Count the Number of Vowels
C++
#include <cstring>
#include <iostream>
using namespace std;
int main()
{
string str = "GeeksforGeeks to the moon";
int vowels = 0;
for (int i = 0; str[i] != '\0'; i++) {
if (str[i] == 'a' || str[i] == 'e' || str[i] == 'i'
|| str[i] == 'o' || str[i] == 'u'
|| str[i] == 'A' || str[i] == 'E'
|| str[i] == 'I' || str[i] == 'O'
|| str[i] == 'U') {
vowels++;
}
}
cout << "Number of vowels in the string: " << vowels
<< endl;
return 0;
}
|
Output
Number of vowels in the string: 9
10. Write a Program to Remove the Vowels from a String
C++
#include <cstring>
#include <iostream>
using namespace std;
int main()
{
int j = 0;
string str = "GeeksforGeeks";
for (int i = 0; str[i] != '\0'; i++) {
if (str[i] != 'a' && str[i] != 'e' && str[i] != 'i'
&& str[i] != 'o' && str[i] != 'u'
&& str[i] != 'A' && str[i] != 'E'
&& str[i] != 'I' && str[i] != 'O'
&& str[i] != 'U') {
str[j++] = str[i];
}
}
while (j < str.size()) {
str[j] = '\0';
j++;
}
cout << "String without vowels: " << str << endl;
return 0;
}
|
Output
String without vowels: GksfrGks
11. Write a Program to Remove All Characters From a String Except Alphabets
C++
#include <cctype>
#include <iostream>
#include <string>
using namespace std;
string remove_non_alphabets(string str)
{
string result = "";
for (char c : str) {
if (isalpha(c)) {
result += c;
}
}
return result;
}
int main()
{
string str = "Gee$ksfor$geeks";
cout << "Alphabets only: " << remove_non_alphabets(str)
<< endl;
return 0;
}
|
Output
Alphabets only: Geeksforgeeks
12. Write a Program to Remove Spaces From a String
C++
#include <iostream>
#include <string>
using namespace std;
string remove_spaces(string str)
{
string result = "";
for (char c : str) {
if (c != ' ') {
result += c;
}
}
return result;
}
int main()
{
string str = "Gfg to the moon";
cout << "Without spaces: " << remove_spaces(str)
<< endl;
return 0;
}
|
Output
Without spaces: Gfgtothemoon
13. Write a Program to Find the Sum of the First N Natural Numbers
C++
#include <iostream>
using namespace std;
int findSum(int n)
{
int sum = 0;
for (int i = 1; i <= n; i++)
sum = sum + i;
return sum;
}
int main()
{
int n = 7;
cout << findSum(n);
return 0;
}
|
14. Write a Program to Find the Factorial of a Number Using Loops
C++
#include <bits/stdc++.h>
using namespace std;
int factorial(int n)
{
int fact = 1;
while (n > 1) {
fact *= n;
n--;
}
return fact;
}
int main()
{
int num = 5;
cout << factorial(num);
return 0;
}
|
15. Write a Program to Find a Leap Year or Not
C++
#include <iostream>
using namespace std;
bool checkYear(int year)
{
if (year % 400 == 0)
return true;
if (year % 100 == 0)
return false;
if (year % 4 == 0)
return true;
return false;
}
int main()
{
int year = 2000;
if (checkYear(year))
cout << "Leap Year";
else
cout << "Not a Leap Year";
return 0;
}
|
16. Write a Program to Check the Prime Number
C++
#include <iostream>
using namespace std;
bool isPrime(int n)
{
if (n <= 1)
return false;
for (int i = 2; i < n; i++)
if (n % i == 0)
return false;
return true;
}
int main()
{
isPrime(21) ? cout << " true\n" : cout << " false\n";
isPrime(17) ? cout << " true\n" : cout << " false\n";
return 0;
}
|
17. Write a Program to Check Palindrome
C++
#include <iostream>
using namespace std;
bool checkPalindrome(int n)
{
int ans = 0;
int temp = n;
while (temp != 0) {
ans = (ans * 10) + (temp % 10);
temp = temp / 10;
}
return (ans == n);
}
int main()
{
int n = 12321;
if (checkPalindrome(n) == 1) {
cout << "Yes\n";
}
else {
cout << "No\n";
}
return 0;
}
|
18. Write a Program to Check Whether a Number is an Armstrong Number or Not
C++
#include <iostream>
using namespace std;
int main()
{
int n = 153;
int temp = n;
int ans = 0;
while (n > 0) {
int rem = n % 10;
ans = (ans) + (rem * rem * rem);
n = n / 10;
}
if (temp == ans) {
cout << ("Yes, it is Armstrong Number");
}
else {
cout << ("No, it is not an Armstrong Number");
}
return 0;
}
|
Output
Yes, it is Armstrong Number
19. Write a Program to Find the Nth Term of the Fibonacci Series
C++
#include <iostream>
using namespace std;
int fib(int n)
{
int first = 0, second = 1, ans;
if (n == 0)
return first;
for (int i = 2; i <= n; i++) {
ans = first + second;
first = second;
second = ans;
}
return ans;
}
int main()
{
int n = 13;
cout << fib(n);
return 0;
}
|
20. Write a Program to Calculate the Greatest Common Divisor of Two Numbers
C++
#include <iostream>
using namespace std;
int gcd(int a, int b)
{
int result = min(a, b);
while (result > 0) {
if (a % result == 0 && b % result == 0) {
break;
}
result--;
}
return result;
}
int main()
{
int a = 54, b = 33;
cout << "GCD: " << gcd(a, b);
return 0;
}
|
21. Write a Program to Calculate the Lowest Common Multiple (LCM) of Two Numbers
C++
#include <iostream>
using namespace std;
long long gcd(long long int a, long long int b)
{
if (b == 0)
return a;
return gcd(b, a % b);
}
long long lcm(int a, int b)
{
long long result = (a / gcd(a, b)) * b;
return result;
}
int main()
{
int a = 24, b = 13;
cout << "LCM : " << lcm(a, b);
return 0;
}
|
22. Write a Program for Finding the Roots of a Quadratic Equation
C++
#include <iostream>
#include <math.h>
using namespace std;
void findRoots(int a, int b, int c)
{
if (a == 0) {
cout << "Invalid";
return;
}
int d = b * b - 4 * a * c;
double sqrt_val = sqrt(abs(d));
if (d > 0) {
cout << "Roots are real and different \n";
cout << (double)(-b + sqrt_val) / (2 * a) << "\n"
<< (double)(-b - sqrt_val) / (2 * a);
}
else if (d == 0) {
cout << "Roots are real and same \n";
cout << -(double)b / (2 * a);
}
else {
cout << "Roots are complex \n";
cout << -(double)b / (2 * a) << " + i"
<< sqrt_val / (2 * a) << "\n"
<< -(double)b / (2 * a) << " - i"
<< sqrt_val / (2 * a);
}
}
int main()
{
int a = 1, b = 4, c = 4;
findRoots(a, b, c);
return 0;
}
|
Output
Roots are real and same
-2
23. Write a Program to Find the Smallest and Largest Element in an Array
C++
#include <iostream>
using namespace std;
void findMinMax(int arr[], int n)
{
int mini = arr[0];
int maxi = arr[0];
for (int i = 0; i < n; i++) {
if (arr[i] < mini) {
mini = arr[i];
}
else if (arr[i] > maxi) {
maxi = arr[i];
}
}
cout << "Min: " << mini << endl;
cout << "Max: " << maxi << endl;
}
int main()
{
int arr[] = { 1, 2, 3, 4, 5 };
int N = sizeof(arr) / sizeof(arr[0]);
findMinMax(arr, N);
return 0;
}
|
24. Write a Program to Find the Second Smallest Element in an Array
C++
#include <climits>
#include <iostream>
using namespace std;
void print2Smallest(int arr[], int n)
{
int first, second;
if (n < 2) {
cout << " Invalid Input ";
return;
}
first = second = INT_MAX;
for (int i = 0; i < n; i++) {
if (arr[i] < first) {
second = first;
first = arr[i];
}
else if (arr[i] < second && arr[i] != first)
second = arr[i];
}
if (second == INT_MAX)
cout << "There is no second smallest element\n";
else
cout << " Second smallest element is " << second
<< endl;
}
int main()
{
int arr[] = { 21, 3, 15, 41, 34, 10 };
int n = sizeof(arr) / sizeof(arr[0]);
print2Smallest(arr, n);
return 0;
}
|
Output
Second smallest element is 10
25. Write a Program to Calculate the Sum of Elements in an Array
C++
#include <iostream>
using namespace std;
int sum(int arr[], int n)
{
int sum = 0;
for (int i = 0; i < n; i++)
sum += arr[i];
return sum;
}
int main()
{
int arr[] = { 1, 23, 54, 12, 9 };
int n = sizeof(arr) / sizeof(arr[0]);
cout << "Sum: " << sum(arr, n);
return 0;
}
|
26. Write a Program to Check if the Given String is Palindrome or Not
C++
#include <iostream>
using namespace std;
string isPalindrome(string S)
{
for (int i = 0; i < S.length() / 2; i++) {
if (S[i] != S[S.length() - i - 1]) {
return "No";
}
}
return "Yes";
}
int main()
{
string S = "GeekeeG";
cout << isPalindrome(S);
return 0;
}
|
27. Write a Program to Check if Two Strings are Anagram or Not
C++
#include <iostream>
using namespace std;
#define NO_OF_CHARS 256
bool areAnagram(char* str1, char* str2)
{
int count1[NO_OF_CHARS] = { 0 };
int count2[NO_OF_CHARS] = { 0 };
int i;
for (i = 0; str1[i] && str2[i]; i++) {
count1[str1[i]]++;
count2[str2[i]]++;
}
if (str1[i] || str2[i])
return false;
for (i = 0; i < NO_OF_CHARS; i++)
if (count1[i] != count2[i])
return false;
return true;
}
int main()
{
char str1[] = "Geek";
char str2[] = "for";
if (areAnagram(str1, str2))
cout << "The two strings are anagram of each other";
else
cout << "The two strings are not anagram of each "
"other";
return 0;
}
|
Output
The two strings are not anagram of each other
28. Write a Program to Print a Diamond Pattern
*
***
*****
*******
*****
***
*
C++
#include <iostream>
using namespace std;
void printDiamond(int n)
{
int space = n - 1;
for (int i = 0; i < n; i++) {
for (int j = 0; j < space; j++)
cout << " ";
for (int j = 0; j <= i; j++)
cout << "* ";
cout << endl;
space--;
}
space = 0;
for (int i = n; i > 0; i--) {
for (int j = 0; j < space; j++)
cout << " ";
for (int j = 0; j < i; j++)
cout << "* ";
cout << endl;
space++;
}
}
int main()
{
printDiamond(5);
return 0;
}
|
Output
*
* *
* * *
* * * *
* * * * *
* * * * *
* * * *
* * *
* *
*
29. Write a Program to Print a Pyramid Pattern
*
***
*****
*******
C++
#include <iostream>
using namespace std;
void pattern(int n)
{
int k = 2 * n - 2;
for (int i = 0; i < n; i++) {
for (int j = 0; j < k; j++)
cout << " ";
k = k - 1;
for (int j = 0; j <= i; j++) {
cout << "* ";
}
cout << endl;
}
}
int main()
{
int n = 5;
pattern(n);
return 0;
}
|
Output
*
* *
* * *
* * * *
* * * * *
30. Write a Program to Print the Hourglass Pattern
* * * * * * * * *
* * * * * * *
* * * * *
* * *
*
* * *
* * * * *
* * * * * * *
* * * * * * * * *
C++
#include <iostream>
using namespace std;
void hourglass(int rows)
{
for (int i = 0; i < 2 * rows - 1; i++) {
int comp;
if (i < rows) {
comp = 2 * i + 1;
}
else {
comp = 2 * (2 * rows - i) - 3;
}
for (int j = 0; j < comp; j++) {
cout << ' ';
}
for (int k = 0; k < 2 * rows - comp; k++) {
cout << "* ";
}
cout << '\n';
}
}
int main()
{
hourglass(5);
return 0;
}
|
Output
* * * * * * * * *
* * * * * * *
* * * * *
* * *
*
* * *
* * * * *
* * * * * * *
* * * * * * * * *
31. Write a Program to Print the Rotated Hourglass Pattern
* *
* * * *
* * * * * *
* * * * * * * *
* * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * *
* * * * * * * *
* * * * * *
* * * *
* *
C++
#include <iostream>
using namespace std;
void pattern(int n)
{
for (int i = 0; i <= n; i++) {
for (int j = 0; j <= i; j++) {
cout << "* ";
}
int spaces = 2 * (n - i);
for (int j = 0; j < spaces; j++) {
cout << " ";
}
for (int j = 0; j <= i; j++) {
cout << "* ";
}
cout << endl;
}
for (int i = n - 1; i >= 0; i--) {
for (int j = 0; j <= i; j++) {
cout << "* ";
}
int spaces = 2 * (n - i);
for (int j = 0; j < spaces; j++) {
cout << " ";
}
for (int j = 0; j <= i; j++) {
cout << "* ";
}
cout << endl;
}
}
int main()
{
int n = 5;
pattern(n);
return 0;
}
|
Output
* *
* * * *
* * * * * *
* * * * * * * *
* * * * * * * * * *
* * * * * * * * * * * *
* * * * * * * * * *
* * * * * * * *
* * * * * *
* * * *
* *
32. Write a Program to Print a Simple Pyramid Pattern
C++
#include <iostream>
using namespace std;
int main()
{
int rows = 5;
for (int i = 1; i <= rows; i++) {
for (int j = rows; j >= i; j--) {
cout << " ";
}
for (int k = 1; k <= (2 * i - 1); k++) {
cout << "*";
}
cout << endl;
}
return 0;
}
|
Output
*
***
*****
*******
*********
33. Write a Program to print an Inverted Pyramid
C++
#include <iostream>
using namespace std;
int main()
{
int rows = 5;
for (int i = rows; i >= 1; i--) {
for (int j = rows; j > i; j--) {
cout << " ";
}
for (int k = 1; k <= (2 * i - 1); k++) {
cout << "*";
}
cout << endl;
}
return 0;
}
|
Output
*********
*******
*****
***
*
34. Write a Program to Print a Triangle Star Pattern
C++
#include <iostream>
using namespace std;
int main()
{
int rows;
rows = 5;
for (int i = 1; i <= rows; i++) {
for (int j = 1; j <= i; j++) {
cout << "*";
}
cout << endl;
}
return 0;
}
|
Output
*
**
***
****
*****
35. Write a Program to Print Floyd’s Triangle
1
2 3
4 5 6
7 8 9 10
C++
#include <stdio.h>
int main()
{
int rows = 4;
int n = 1;
for (int i = 0; i < rows; i++) {
for (int j = 0; j <= i; j++) {
printf("%d ", n++);
}
printf("\n");
}
return 0;
}
|
Output
1
2 3
4 5 6
7 8 9 10
36. Write a Program to Print the Pascal Triangle
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
C++
#include <iostream>
using namespace std;
void printPascal(int n)
{
int arr[n][n];
for (int line = 0; line < n; line++) {
for (int i = 0; i <= line; i++) {
if (line == i || i == 0)
arr[line][i] = 1;
else
arr[line][i] = arr[line - 1][i - 1]
+ arr[line - 1][i];
cout << arr[line][i] << " ";
}
cout << "\n";
}
}
int main()
{
int n = 6;
printPascal(n);
return 0;
}
|
Output
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
37. Write a Program to Print the Given String in Reverse Order
C++
#include <cstring>
#include <iostream>
using namespace std;
int main()
{
int len;
string str = "GeeksforGeeks";
len = str.size();
cout << "Reverse of the string: ";
for (int i = len - 1; i >= 0; i--) {
cout << str[i];
}
cout << endl;
return 0;
}
|
Output
Reverse of the string: skeeGrofskeeG
38. Write a C++ Program to Print the Given String in Reverse Order Using Recursion
C++
#include <iostream>
using namespace std;
void reverse_str(string& s, int n, int i)
{
if (n <= i) {
return;
}
swap(s[i], s[n]);
reverse_str(s, n - 1, i + 1);
}
int main()
{
string str = "GeeksforGeeks";
reverse_str(str, str.length() - 1, 0);
cout << str << endl;
}
|
39. Write a Program to Check if the Given String is Palindrome or not Using Recursion
C++
#include <bits/stdc++.h>
using namespace std;
bool isPalRec(char str[], int s, int n)
{
if (s == n)
return true;
if (str[s] != str[n])
return false;
if (s < n + 1)
return isPalRec(str, s + 1, n - 1);
return true;
}
bool isPalindrome(char str[])
{
int n = strlen(str);
if (n == 0)
return true;
return isPalRec(str, 0, n - 1);
}
int main()
{
char str[] = "GeeKeeG";
if (isPalindrome(str))
cout << "Yes";
else
cout << "No";
return 0;
}
|
40. Write a Program to Calculate the Length of the String Using Recursion
C++
#include <iostream>
using namespace std;
int cal(char* str)
{
if (*str == '\0')
return 0;
else
return 1 + cal(str + 1);
}
int main()
{
char str[] = "GeeksforGeeks";
cout << cal(str);
return 0;
}
|
41. Write a Program to Calculate the Factorial of a Number Using Recursion
C++
#include <iostream>
using namespace std;
unsigned long long factorial(unsigned long long n)
{
if (n == 0 || n == 1)
return 1;
return n * factorial(n - 1);
}
int main()
{
unsigned long long num = 15;
cout << "Factorial of " << num << " is "
<< factorial(num) << endl;
return 0;
}
|
Output
Factorial of 15 is 1307674368000
42. Write a Program to Count the Sum of Numbers in a String
C++
#include <iostream>
#include <sstream>
#include <string>
using namespace std;
int sum_of_numbers(string str)
{
int sum = 0;
for (char ch : str) {
if (isdigit(ch)) {
sum += ch - '0';
}
}
return sum;
}
int main()
{
string str;
str = "1234";
cout << "Sum of numbers: " << sum_of_numbers(str)
<< endl;
return 0;
}
|
Output
Sum of numbers: 10
43. Write a Program to Print All Natural Numbers up to N Without Using a Semi-Colon
C++
#include <iostream>
using namespace std;
#define N 10
int main()
{
static int x = 1;
if (cout << x << " " && x++ < N && main()) {
}
return 0;
}
|
Output
1 2 3 4 5 6 7 8 9 10
44. Write a Program to Swap the Values of Two Variables Without Using any Extra Variable
C++
#include <iostream>
using namespace std;
int main()
{
int x = 3;
int y = 4;
cout << "X : " << x << endl;
cout << "Y : " << y << endl;
x = x + y;
y = x - y;
x = x - y;
cout << endl;
cout << "After:" << endl;
cout << "X : " << x << endl;
cout << "Y : " << y << endl;
return 0;
}
|
Output
X : 3
Y : 4
After:
X : 4
Y : 3
45. Write a Program to Print the Maximum Value of an Unsigned int Using One’s Complement (~) Operator
C++
#include <iostream>
using namespace std;
int main()
{
unsigned int max;
max = 0;
max = ~max;
cout << "Max value possible : " << max;
return 0;
}
|
Output
Max value possible : 4294967295
46. Write a Program to Check for the Equality of Two Numbers Without Using Arithmetic or Comparison Operator
C++
#include <iostream>
using namespace std;
int main()
{
int a = 10, b = 10;
if (a ^ b)
cout << "Not-Equal";
else
cout << "Equal";
return 0;
}
|
47. Write a Program to Find the Maximum and Minimum of the Two Numbers Without Using the Comparison Operator
C++
#include <iostream>
using namespace std;
int main()
{
int a = 5, b = 10;
cout << "max :" << (((a + b) + abs(a - b)) / 2) << endl;
cout << "min :" << (((a + b) - abs(a - b)) / 2) << endl;
return 0;
}
|
48. Write a Program for Octal to Decimal Conversion
C++
#include <cmath>
#include <iostream>
using namespace std;
int main()
{
int oct, dec = 0, place = 0;
oct = 67;
int temp = oct;
while (temp) {
int lastDigit = temp % 10;
temp /= 10;
dec += lastDigit * pow(8, place);
++place;
}
cout << "Decimal equivalent is: " << dec << endl;
return 0;
}
|
Output
Decimal equivalent is: 55
49. Write a Program for Hexadecimal to Decimal Conversion
C++
#include <cmath>
#include <iostream>
using namespace std;
int hexToDecimal(char hexDigit)
{
if (hexDigit >= '0' && hexDigit <= '9') {
return int(hexDigit - '0');
}
else if (hexDigit >= 'A' && hexDigit <= 'F') {
return int(hexDigit - 'A' + 10);
}
else if (hexDigit >= 'a' && hexDigit <= 'f') {
return int(hexDigit - 'a' + 10);
}
return -1;
}
int main()
{
string hex;
int decimal = 0, place = 0;
hex = "67";
int n = hex.length();
for (int i = n - 1; i >= 0; i--) {
int digit = hexToDecimal(hex[i]);
decimal += digit * pow(16, place);
place++;
}
cout << "Decimal equivalent " << decimal << endl;
return 0;
}
|
Output
Decimal equivalent 103
50. Write a Program for Decimal to Binary Conversion
C++
#include <bitset>
#include <iostream>
using namespace std;
int main()
{
int decimal = 7;
bitset<32> binary(decimal);
cout << "Binary equivalent: " << binary << endl;
return 0;
}
|
Output
Binary equivalent: 00000000000000000000000000000111
51. Write a Program for Decimal Octal Conversion
C++
#include <cmath>
#include <iostream>
using namespace std;
int main()
{
int decimal, octal = 0, place = 1;
decimal = 55;
int temp = decimal;
while (temp) {
int lastDigit = temp % 8;
temp /= 8;
octal += lastDigit * place;
place *= 10;
}
cout << "Octal equivalent " << octal << endl;
return 0;
}
|
Output
Octal equivalent 67
52. Write a Program for Decimal to Hexadecimal Conversion
C++
#include <cmath>
#include <iostream>
#include <string>
using namespace std;
string decimalToHexa(int decimal)
{
string hexadecimal = "";
char hexaDecimals[16]
= { '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
while (decimal > 0) {
int remainder = decimal % 16;
hexadecimal = hexaDecimals[remainder] + hexadecimal;
decimal /= 16;
}
return hexadecimal;
}
int main()
{
int decimal = 103;
cout << "Hexadecimal equivalent: "
<< decimalToHexa(decimal) << endl;
return 0;
}
|
Output
Hexadecimal equivalent: 67
53. Write a Program for Binary to Octal Conversion
C++
#include <bits/stdc++.h>
using namespace std;
void createMap(unordered_map<string, char>* um)
{
(*um)["000"] = '0';
(*um)["001"] = '1';
(*um)["010"] = '2';
(*um)["011"] = '3';
(*um)["100"] = '4';
(*um)["101"] = '5';
(*um)["110"] = '6';
(*um)["111"] = '7';
}
string convertBinToOct(string bin)
{
int l = bin.size();
int t = bin.find_first_of('.');
int len_left = t != -1 ? t : l;
for (int i = 1; i <= (3 - len_left % 3) % 3; i++)
bin = '0' + bin;
if (t != -1) {
int len_right = l - len_left - 1;
for (int i = 1; i <= (3 - len_right % 3) % 3; i++)
bin = bin + '0';
}
unordered_map<string, char> bin_oct_map;
createMap(&bin_oct_map);
int i = 0;
string octal = "";
while (1) {
octal += bin_oct_map[bin.substr(i, 3)];
i += 3;
if (i == bin.size())
break;
if (bin.at(i) == '.') {
octal += '.';
i++;
}
}
return octal;
}
int main()
{
string bin = "1111001010010100001.010110110011011";
cout << "Octal number = " << convertBinToOct(bin);
return 0;
}
|
Output
Octal number = 1712241.26633
54. Write a Program for Octal to Binary Conversion
C++
#include <iostream>
using namespace std;
string OctToBin(string octnum)
{
long int i = 0;
string binary = "";
while (octnum[i]) {
switch (octnum[i]) {
case '0':
binary += "000";
break;
case '1':
binary += "001";
break;
case '2':
binary += "010";
break;
case '3':
binary += "011";
break;
case '4':
binary += "100";
break;
case '5':
binary += "101";
break;
case '6':
binary += "110";
break;
case '7':
binary += "111";
break;
default:
cout << "\nInvalid Octal Digit " << octnum[i];
break;
}
i++;
}
return binary;
}
int main()
{
string octnum = "345";
cout << "Equivalent Binary Value = "
<< OctToBin(octnum);
return 0;
}
|
Output
Equivalent Binary Value = 011100101
55. Write a Program to Implement the Use of Encapsulation
C++
#include <iostream>
using namespace std;
class Encapsulation {
private:
int x;
public:
void setter(int a) { x = a; }
int getter() { return x; }
};
int main()
{
Encapsulation obj;
obj.setter(13);
cout << obj.getter();
return 0;
}
|
56. Write a Program to Implement the Concept of Abstraction
C++
#include <iostream>
using namespace std;
class implementAbstraction {
private:
int p, q;
public:
void setter(int x, int y)
{
p = x;
q = y;
}
void display()
{
cout << "p = " << p << endl;
cout << "q = " << q << endl;
}
};
int main()
{
implementAbstraction obj;
obj.setter(1, 2);
obj.display();
return 0;
}
|
57. Write a Program to Implement the Concept of Compile-Time Polymorphism or Function Overloading
C++
#include <iostream>
using namespace std;
class Geeks {
public:
void func(int x)
{
cout << "value of x is " << x << endl;
}
void func(double x)
{
cout << "value of x is " << x << endl;
}
void func(int x, int y)
{
cout << "value of x and y is " << x << ", " << y
<< endl;
}
};
int main()
{
Geeks obj1;
obj1.func(10);
obj1.func(5.321);
obj1.func(94, 32);
return 0;
}
|
Output
value of x is 10
value of x is 5.321
value of x and y is 94, 32
58. Write a Program to Implement the Concept of Operator Overloading
C++
#include <iostream>
using namespace std;
class Complex {
private:
int real, imag;
public:
Complex(int r = 0, int i = 0)
{
real = r;
imag = i;
}
Complex operator+(Complex const& obj)
{
Complex res;
res.real = real + obj.real;
res.imag = imag + obj.imag;
return res;
}
void print() { cout << real << " + " << imag << "i\n"; }
};
int main()
{
Complex c1(15, 5), c2(3, 5);
Complex c3 = c1 + c2;
c3.print();
}
|
59. Write a Program to Implement the Concept of Function Overriding or Runtime Polymorphism
C++
#include <iostream>
using namespace std;
class base {
public:
virtual void print()
{
cout << "print base class" << endl;
}
void show() { cout << "show base class" << endl; }
};
class derived : public base {
public:
void print() { cout << "print derived class" << endl; }
void show() { cout << "show derived class" << endl; }
};
int main()
{
base* bptr;
derived d;
bptr = &d;
bptr->print();
bptr->show();
return 0;
}
|
Output
print derived class
show base class
60. Write a Program to Implement Single-Level Inheritance
C++
#include <iostream>
#include <string.h>
using namespace std;
class Person {
int id;
char name[100];
public:
void set_p(int id, char* name)
{
strcpy(this->name, name);
this->id = id;
}
void display_p()
{
cout << endl << id << "\t" << name << "\t";
}
};
class Student : private Person {
char course[50];
int fee;
public:
void set_s(int id, char* name, char* course, int fee)
{
set_p(id, name);
strcpy(this->course, course);
this->fee = fee;
}
void display_s()
{
display_p();
cout << course << "\t" << fee << endl;
}
};
main()
{
Student s;
char name[] = "XYZ";
char course[] = "ABC";
s.set_s(132451, name, course, 100000);
s.display_s();
return 0;
}
|
Output
132451 XYZ ABC 100000
61. Write a Program to Create a Class for Complex Numbers
C++
#include <bits/stdc++.h>
using namespace std;
struct c {
double real;
double img;
};
class Complex {
private:
struct c num;
public:
Complex() {}
Complex(double real, double img)
{
num.img = img;
num.real = real;
}
Complex(Complex& var)
{
num.img = var.num.img;
num.real = var.num.real;
}
void print()
{
cout << num.real << " + i" << num.img << endl;
}
double imag() { return num.img; }
double real() { return num.real; }
Complex operator+(Complex& obj1)
{
Complex var;
var.num.real = num.real + obj1.num.real;
var.num.img = num.img + obj1.num.img;
return var;
}
Complex operator-(Complex& obj1)
{
Complex var;
var.num.real = num.real - obj1.num.real;
var.num.img = num.img - obj1.num.img;
return var;
}
Complex operator*(Complex& obj1)
{
Complex var;
var.num.real = num.real * obj1.num.real
- num.img * obj1.num.img;
var.num.img = num.real * obj1.num.img
+ num.img * obj1.num.real;
return var;
}
};
int main()
{
Complex a(11, 12), b(5, 8);
Complex c;
c = a + b;
a.print();
b.print();
c.print();
return 0;
}
|
Output
11 + i12
5 + i8
16 + i20
62. Write a Program to Implement the Inch Feet System
C++
#include <bits/stdc++.h>
using namespace std;
struct c {
double feet;
double inch;
};
class inchFeet {
private:
struct c length;
public:
inchFeet() {}
inchFeet(double feet, double inch)
{
length.inch = inch;
length.feet = feet;
}
inchFeet(inchFeet& var)
{
length.inch = var.length.inch;
length.feet = var.length.feet;
}
void print()
{
cout << length.feet << " feet and " << length.inch
<< " inches" << endl;
}
double inches() { return length.inch; }
double feet() { return length.feet; }
inchFeet operator+(inchFeet& obj1)
{
inchFeet var;
var.length.feet = length.feet + obj1.length.feet;
var.length.inch = length.inch + obj1.length.inch;
if (var.length.inch >= 12.0) {
var.length.feet++;
var.length.inch - 12.0;
}
return var;
}
inchFeet operator-(inchFeet& obj1)
{
inchFeet var;
struct c temp = length;
if (temp.feet > obj1.length.feet) {
if (temp.inch < obj1.length.inch) {
temp.feet--;
temp.inch += 12;
}
var.length.feet = temp.feet - obj1.length.feet;
var.length.inch = temp.inch - obj1.length.inch;
}
else {
cout << "Negative Length is not Possible\n";
}
return var;
}
};
int main()
{
inchFeet a(11, 4), b(5, 8);
inchFeet c;
c = a - b;
a.print();
b.print();
c.print();
return 0;
}
|
Output
11 feet and 4 inches
5 feet and 8 inches
5 feet and 8 inches
63. Write a Program to Implement Bubble Sort
C++
#include <iostream>
using namespace std;
void bubbleSort(int arr[], int n)
{
int i, j;
for (i = 0; i < n - 1; i++)
for (j = 0; j < n - i - 1; j++)
if (arr[j] > arr[j + 1])
swap(arr[j], arr[j + 1]);
}
void printArray(int arr[], int size)
{
int i;
for (i = 0; i < size; i++)
cout << arr[i] << " ";
cout << endl;
}
int main()
{
int arr[] = { 3, 1, 4, 2, 5 };
int N = sizeof(arr) / sizeof(arr[0]);
bubbleSort(arr, N);
cout << "Sorted array: ";
printArray(arr, N);
return 0;
}
|
Output
Sorted array: 1 2 3 4 5
64. Write a Program to Implement Insertion Sort
C++
#include <bits/stdc++.h>
using namespace std;
void insertion_sort(int arr[], int n)
{
int i, key, j;
for (i = 1; i < n; i++) {
key = arr[i];
j = i - 1;
while (j >= 0 && arr[j] > key) {
arr[j + 1] = arr[j];
j = j - 1;
}
arr[j + 1] = key;
}
}
void print_array(int arr[], int n)
{
cout << " Sorted array:";
for (int i = 0; i < n; i++)
cout << arr[i] << " ";
cout << endl;
}
int main()
{
int arr[] = { 1, 4, 3, 2, 5 };
int N = sizeof(arr) / sizeof(arr[0]);
insertion_sort(arr, N);
print_array(arr, N);
return 0;
}
|
Output
Sorted array:1 2 3 4 5
65. Write a Program to Implement Selection Sort
C++
#include <iostream>
using namespace std;
void swap(int* p, int* q)
{
int temp = *p;
*p = *q;
*q = temp;
}
void selectionSort(int arr[], int n)
{
int min_index;
for (int i = 0; i < n - 1; i++) {
min_index = i;
for (int j = i + 1; j < n; j++)
if (arr[j] < arr[min_index])
min_index = j;
if (min_index != i)
swap(&arr[min_index], &arr[i]);
}
}
void printArray(int arr[], int size)
{
int i;
for (i = 0; i < size; i++)
cout << arr[i] << " ";
cout << endl;
}
int main()
{
int arr[] = { 5, 4, 3, 2, 1 };
int n = sizeof(arr) / sizeof(arr[0]);
selectionSort(arr, n);
cout << "Sorted array: ";
printArray(arr, n);
return 0;
}
|
Output
Sorted array: 1 2 3 4 5
66. Write a Program to Implement Merge Sort
C++
#include <iostream>
using namespace std;
void merge(int array[], int const left, int const mid,
int const right)
{
auto const subArrayOne = mid - left + 1;
auto const subArrayTwo = right - mid;
auto *leftArray = new int[subArrayOne],
*rightArray = new int[subArrayTwo];
for (auto i = 0; i < subArrayOne; i++)
leftArray[i] = array[left + i];
for (auto j = 0; j < subArrayTwo; j++)
rightArray[j] = array[mid + 1 + j];
auto indexOfSubArrayOne = 0, indexOfSubArrayTwo = 0;
int indexOfMergedArray = left;
while (indexOfSubArrayOne < subArrayOne
&& indexOfSubArrayTwo < subArrayTwo) {
if (leftArray[indexOfSubArrayOne]
<= rightArray[indexOfSubArrayTwo]) {
array[indexOfMergedArray]
= leftArray[indexOfSubArrayOne];
indexOfSubArrayOne++;
}
else {
array[indexOfMergedArray]
= rightArray[indexOfSubArrayTwo];
indexOfSubArrayTwo++;
}
indexOfMergedArray++;
}
while (indexOfSubArrayOne < subArrayOne) {
array[indexOfMergedArray]
= leftArray[indexOfSubArrayOne];
indexOfSubArrayOne++;
indexOfMergedArray++;
}
while (indexOfSubArrayTwo < subArrayTwo) {
array[indexOfMergedArray]
= rightArray[indexOfSubArrayTwo];
indexOfSubArrayTwo++;
indexOfMergedArray++;
}
delete[] leftArray;
delete[] rightArray;
}
void mergeSort(int array[], int const begin, int const end)
{
if (begin >= end)
return;
auto mid = begin + (end - begin) / 2;
mergeSort(array, begin, mid);
mergeSort(array, mid + 1, end);
merge(array, begin, mid, end);
}
void print_array(int A[], int size)
{
for (auto i = 0; i < size; i++)
cout << A[i] << " ";
}
int main()
{
int arr[] = { 5, 6, 3, 10, 1, 4, 9 };
auto arr_size = sizeof(arr) / sizeof(arr[0]);
cout << "Array: ";
print_array(arr, arr_size);
mergeSort(arr, 0, arr_size - 1);
cout << "\nSorted array: ";
print_array(arr, arr_size);
return 0;
}
|
Output
Array: 5 6 3 10 1 4 9
Sorted array: 1 3 4 5 6 9 10
67. Write a Program to Implement Quick Sort
C++
#include <iostream>
using namespace std;
void swap(int* a, int* b)
{
int t = *a;
*a = *b;
*b = t;
}
int partition(int arr[], int low, int high)
{
int pivot = arr[high];
int i = (low - 1);
for (int j = low; j <= high - 1; j++) {
if (arr[j] < pivot) {
i++;
swap(&arr[i], &arr[j]);
}
}
swap(&arr[i + 1], &arr[high]);
return (i + 1);
}
void quickSort(int arr[], int low, int high)
{
if (low < high) {
int pi = partition(arr, low, high);
quickSort(arr, low, pi - 1);
quickSort(arr, pi + 1, high);
}
}
void printArray(int arr[], int size)
{
int i;
for (i = 0; i < size; i++)
cout << arr[i] << " ";
cout << endl;
}
int main()
{
int arr[] = { 2, 5, 6, 9, 1, 3, 4 };
int n = sizeof(arr) / sizeof(arr[0]);
cout << "Array: ";
printArray(arr, n);
quickSort(arr, 0, n - 1);
cout << "Sorted array: ";
printArray(arr, n);
return 0;
}
|
Output
Array: 2 5 6 9 1 3 4
Sorted array: 1 2 3 4 5 6 9
68. Write a Program to Implement Linear Search
C++
#include <iostream>
using namespace std;
int search(int arr[], int N, int x)
{
int i;
for (i = 0; i < N; i++)
if (arr[i] == x)
return i;
return -1;
}
int main()
{
int arr[] = { 5, 4, 1, 6, 10, 9, 23, 2 };
int x = 9;
int N = sizeof(arr) / sizeof(arr[0]);
int result = search(arr, N, x);
if (result == -1)
cout << "Element is not present in array";
else
cout << "Element is present at index " << result;
return 0;
}
|
Output
Element is present at index 5
69. Write a Program to Implement Binary Search
C++
#include <iostream>
using namespace std;
int binarySearch(int arr[], int l, int r, int x)
{
if (r >= l) {
int mid = l + (r - l) / 2;
if (arr[mid] == x)
return mid;
if (arr[mid] > x)
return binarySearch(arr, l, mid - 1, x);
return binarySearch(arr, mid + 1, r, x);
}
return -1;
}
int main(void)
{
int arr[] = { 1, 2, 3, 4, 5, 6 };
int x = 5;
int n = sizeof(arr) / sizeof(arr[0]);
int result = binarySearch(arr, 0, n - 1, x);
if (result == -1)
cout << "Element is not present in array";
else
cout << "Element is present at index " << result;
return 0;
}
|
Output
Element is present at index 4
70. Write a Program to Find the Index of a Given Element in a Vector
C++
#include <bits/stdc++.h>
using namespace std;
void print_index(vector<int> v, int element)
{
auto it = find(v.begin(), v.end(), element);
if (it != v.end()) {
int index = it - v.begin();
cout << index << endl;
}
else {
cout << "-1" << endl;
}
}
int main()
{
vector<int> v = { 1, 2, 3, 4, 5, 6 };
int element = 5;
print_index(v, element);
return 0;
}
|
71. Write a Program to Remove Duplicate Elements in an Array Using STL
C++
#include <bits/stdc++.h>
using namespace std;
void removeDuplicates(int arr[], int n)
{
int i;
set<int> s;
for (i = 0; i < n; i++) {
s.insert(arr[i]);
}
set<int>::iterator it;
cout << "\nAfter removing duplicates:\n";
for (it = s.begin(); it != s.end(); ++it)
cout << *it << " ";
cout << '\n';
}
int main()
{
int arr[] = { 1, 2, 2, 4, 3, 3, 2, 1 };
int n = sizeof(arr) / sizeof(arr[0]);
cout << "\nBefore removing duplicates:\n";
for (int i = 0; i < n; i++)
cout << arr[i] << " ";
removeDuplicates(arr, n);
return 0;
}
|
Output
Before removing duplicates:
1 2 2 4 3 3 2 1
After removing duplicates:
1 2 3 4
72. Write a Program to Sort an Array in Descending Order Using STL
C++
#include <bits/stdc++.h>
using namespace std;
int main()
{
int arr[] = { 1, 2, 3, 4, 5, 6 };
int n = sizeof(arr) / sizeof(arr[0]);
cout << "Array: ";
for (int i = 0; i < n; i++)
cout << arr[i] << " ";
sort(arr, arr + n, greater<int>());
cout << "\nDescending Sorted Array:";
for (int i = 0; i < n; i++)
cout << arr[i] << " ";
return 0;
}
|
Output
Array: 1 2 3 4 5 6
Descending Sorted Array:6 5 4 3 2 1
73. Write a Program to Calculate the Frequency of Each Word in the Given String
C++
#include <bits/stdc++.h>
using namespace std;
void printFrequency(string str)
{
map<string, int> M;
string word = "";
for (int i = 0; i < str.size(); i++) {
if (str[i] == ' ') {
if (M.find(word) == M.end()) {
M.insert(make_pair(word, 1));
word = "";
}
else {
M[word]++;
word = "";
}
}
else
word += str[i];
}
if (M.find(word) == M.end())
M.insert(make_pair(word, 1));
else
M[word]++;
for (auto& it : M) {
cout << it.first << " - " << it.second << endl;
}
}
int main()
{
string str = "Geeks For Geeks is for Geeks";
printFrequency(str);
return 0;
}
|
Output
For - 1
Geeks - 3
for - 1
is - 1
74. Write a Program to Find k Maximum Elements of an Array in the Original Order
C++
#include <bits/stdc++.h>
using namespace std;
void printMax(int arr[], int n, int k)
{
int result[n], c[n];
for (int i = 0; i < n; i++) {
c[i] = arr[i];
result[i] = 0;
}
for (int i = 0; i < k; i++) {
int maxi = INT_MIN;
int index;
for (int j = 0; j < n; j++) {
if (arr[j] > maxi) {
maxi = arr[j];
index = j;
}
}
result[index] = 1;
arr[index] = INT_MIN;
}
for (int i = 0; i < n; i++) {
if (result[i] == 1)
cout << c[i] << " ";
}
}
int main()
{
int arr[] = { 50, 8, 45, 12, 25, 40, 84 };
int n = sizeof(arr) / sizeof(arr[0]);
int k = 3;
printMax(arr, n, k);
return 0;
}
|
75. Write a Program to Find All Unique Subsets of a Given Set Using STL
C++
#include <bits/stdc++.h>
using namespace std;
void solve(vector<int>& arr, int n, set<vector<int> >& ans,
vector<int> v, int i)
{
if (i >= n) {
ans.insert(v);
return;
}
solve(arr, n, ans, v, i + 1);
v.push_back(arr[i]);
solve(arr, n, ans, v, i + 1);
}
vector<vector<int> > AllSubsets(vector<int> arr, int n)
{
set<vector<int> > ans;
sort(arr.begin(), arr.end());
vector<int> v;
solve(arr, n, ans, v, 0);
vector<vector<int> > res;
while (!ans.empty()) {
res.push_back(*ans.begin());
ans.erase(ans.begin());
}
return res;
}
void print(int N, vector<int>& A)
{
vector<vector<int> > result = AllSubsets(A, N);
for (int i = 0; i < result.size(); i++) {
cout << '(';
for (int j = 0; j < result[i].size(); j++) {
cout << result[i][j];
if (j < result[i].size() - 1)
cout << " ";
}
cout << "), ";
}
cout << "\n";
}
int main()
{
int N = 3;
vector<int> A = { 1, 2, 3 };
print(N, A);
return 0;
}
|
Output
(), (1), (1 2), (1 2 3), (1 3), (2), (2 3), (3),
76. Write a Program to Iterate Over a Queue Without Removing the Element
C++
#include <iostream>
#include <queue>
using namespace std;
int main()
{
queue<int> q;
q.push(1);
q.push(2);
q.push(3);
q.push(4);
q.push(5);
queue<int> copy_queue = q;
cout << "Queue elements :\n";
while (!copy_queue.empty()) {
cout << copy_queue.front() << " ";
copy_queue.pop();
}
return 0;
}
|
Output
Queue elements :
1 2 3 4 5
77. Write a Program for the Implementation of Stacks Using an Array
C++
#include <iostream>
using namespace std;
#define MAX 100
class Stack {
private:
int top;
int arr[MAX];
public:
Stack() { top = -1; }
void push(int x)
{
if (top == MAX - 1) {
cout << "Stack overflow" << endl;
return;
}
arr[++top] = x;
}
int pop()
{
if (top == -1) {
cout << "Stack underflow" << endl;
return -1;
}
return arr[top--];
}
bool isEmpty() { return (top == -1); }
int peek()
{
if (top == -1) {
cout << "Stack is empty" << endl;
return -1;
}
return arr[top];
}
};
int main()
{
Stack s;
s.push(1);
s.push(2);
s.push(3);
s.push(4);
s.push(5);
cout << "Popped element: " << s.pop() << endl;
cout << "Top element: " << s.peek() << endl;
return 0;
}
|
Output
Popped element: 5
Top element: 4
78. Write a Program for the Implementation of a Queue Using an Array
C++
#include <iostream>
using namespace std;
#define MAX 100
class Queue {
private:
int front, rear;
int arr[MAX];
public:
Queue() { front = rear = -1; }
void enqueue(int x)
{
if (rear == MAX - 1) {
cout << "Error: Queue overflow" << endl;
return;
}
arr[++rear] = x;
if (front == -1)
front = 0;
}
int dequeue()
{
if (front == -1) {
cout << "Queue underflow" << endl;
return -1;
}
int x = arr[front];
if (front == rear)
front = rear = -1;
else
front++;
return x;
}
bool isEmpty() { return (front == -1); }
int peek()
{
if (front == -1) {
cout << "Queue is empty" << endl;
return -1;
}
return arr[front];
}
};
int main()
{
Queue q;
q.enqueue(1);
q.enqueue(2);
q.enqueue(3);
q.enqueue(4);
q.enqueue(5);
cout << "Dequeued element: " << q.dequeue() << endl;
cout << "Front element: " << q.peek() << endl;
return 0;
}
|
Output
Dequeued element: 1
Front element: 2
79. Write a Program Implementation of Stacks Using a Queue
C++
#include <bits/stdc++.h>
using namespace std;
class Stack {
queue<int> q1, q2;
public:
void push(int x)
{
q2.push(x);
while (!q1.empty()) {
q2.push(q1.front());
q1.pop();
}
queue<int> q = q1;
q1 = q2;
q2 = q;
}
void pop()
{
if (q1.empty())
return;
q1.pop();
}
int top()
{
if (q1.empty())
return -1;
return q1.front();
}
int size() { return q1.size(); }
};
int main()
{
Stack s;
s.push(1);
s.push(2);
s.push(3);
s.push(4);
cout << "Size: " << s.size() << endl;
cout << s.top() << endl;
s.pop();
cout << s.top() << endl;
s.pop();
cout << s.top() << endl;
cout << "Size: " << s.size() << endl;
return 0;
}
|
Output
Size: 4
4
3
2
Size: 2
80. Write a Program to Implement a Stack Using the List in STL
C++
#include <bits/stdc++.h>
using namespace std;
template <typename T> class Stack {
public:
list<T> l;
int cs = 0;
void push(T d)
{
cs++;
l.push_front(d);
}
void pop()
{
if (cs <= 0) {
cout << "Stack empty" << endl;
}
else {
cs--;
l.pop_front();
}
}
bool empty() { return cs == 0; }
T top() { return l.front(); }
int size()
{
return cs;
}
void print()
{
for (auto x : l) {
cout << x << endl;
}
}
};
int main()
{
Stack<int> s;
s.push(1);
s.push(2);
s.push(3);
s.push(4);
cout << "Size: " << s.size() << endl;
cout << "Top element:" << s.top() << endl;
s.pop();
cout << "Top element:" << s.top() << endl;
s.pop();
cout << "Top element:" << s.top() << endl;
cout << "Size:" << s.size() << endl;
return 0;
}
|
Output
Size: 4
Top element:4
Top element:3
Top element:2
Size:2
81. Write a Program to Determine Array is a Subset of Another Array or Not
C++
#include <iostream>
using namespace std;
bool isSubset(int arr1[], int arr2[], int m, int n)
{
int i = 0;
int j = 0;
for (i = 0; i < n; i++) {
for (j = 0; j < m; j++) {
if (arr2[i] == arr1[j])
break;
}
if (j == m)
return 0;
}
return 1;
}
int main()
{
int arr1[] = { 1, 11, 31, 21, 30, 17 };
int arr2[] = { 11, 30, 17, 1 };
int m = sizeof(arr1) / sizeof(arr1[0]);
int n = sizeof(arr2) / sizeof(arr2[0]);
if (isSubset(arr1, arr2, m, n))
cout << "arr2 is subset of arr1 ";
else
cout << "arr2 is not a subset of arr1";
return 0;
}
|
Output
arr2 is subset of arr1
82. Write a Program for Finding the Circular Rotation of an Array by K Positions
C++
#include <iostream>
using namespace std;
void Rotate(int arr[], int k, int n)
{
int temp[n];
int t = 0;
for (int i = k; i < n; i++) {
temp[t] = arr[i];
t++;
}
for (int i = 0; i < k; i++) {
temp[t] = arr[i];
t++;
}
for (int i = 0; i < n; i++) {
arr[i] = temp[i];
}
}
void print_array(int arr[], int n)
{
for (int i = 0; i < n; i++) {
cout << arr[i] << " ";
}
}
int main()
{
int arr[] = { 1, 2, 3, 4, 5 };
int N = sizeof(arr) / sizeof(arr[0]);
int k = 2;
Rotate(arr, k, N);
print_array(arr, N);
return 0;
}
|
83. Write a Program to Sort the First Half in Ascending Order and the Second Half in Descending
C++
#include <iostream>
using namespace std;
void ascDecFunc(int a[], int n)
{
int temp;
for (int i = 0; i < n - 1; i++) {
for (int j = 0; j < n / 2; j++) {
if (a[j] > a[j + 1]) {
temp = a[j];
a[j] = a[j + 1];
a[j + 1] = temp;
}
}
for (int j = n / 2; j < n - 1; j++) {
if (a[j] < a[j + 1]) {
temp = a[j];
a[j] = a[j + 1];
a[j + 1] = temp;
}
}
}
for (int i = 0; i < n; i++)
cout << a[i] << " ";
}
int main()
{
int arr[] = { 1, 2, 3, 4, 5, 6, 7, 8 };
int len = sizeof(arr) / sizeof(arr[0]);
ascDecFunc(arr, len);
return 0;
}
|
84. Write a Program to Print the Given String in Reverse Order
C++
#include <iostream>
using namespace std;
void reverse(string str)
{
for (int i = str.length() - 1; i >= 0; i--)
cout << str[i];
}
int main(void)
{
string str = "GeeksforGeeks";
reverse(str);
return (0);
}
|
85. Write a Program to Print All Permutations of a String Using Recursion
C++
#include <iostream>
#include <string>
using namespace std;
void permute(string s, string answer)
{
if (s.length() == 0) {
cout << answer << endl;
return;
}
for (int i = 0; i < s.length(); i++) {
char ch = s[i];
string left = s.substr(0, i);
string right = s.substr(i + 1);
string result = left + right;
permute(result, answer + ch);
}
}
int main()
{
string s = "ABC";
string answer = "";
permute(s, answer);
return 0;
}
|
Output
ABC
ACB
BAC
BCA
CAB
CBA
86. Write a Program to Print All Permutations of a Given String in Lexicographically Sorted Order
C++
#include <bits/stdc++.h>
using namespace std;
int compare(const void* a, const void* b)
{
return (*(char*)a - *(char*)b);
}
void swap(char* a, char* b)
{
char t = *a;
*a = *b;
*b = t;
}
int findCeil(char str[], char first, int l, int h)
{
int ceilIndex = l;
for (int i = l + 1; i <= h; i++)
if (str[i] > first && str[i] < str[ceilIndex])
ceilIndex = i;
return ceilIndex;
}
void Permutations(char str[])
{
int size = strlen(str);
qsort(str, size, sizeof(str[0]), compare);
bool isFinished = false;
while (!isFinished) {
cout << str << endl;
int i;
for (i = size - 2; i >= 0; --i)
if (str[i] < str[i + 1])
break;
if (i == -1)
isFinished = true;
else {
int ceilIndex
= findCeil(str, str[i], i + 1, size - 1);
swap(&str[i], &str[ceilIndex]);
qsort(str + i + 1, size - i - 1, sizeof(str[0]),
compare);
}
}
}
int main()
{
char str[] = "XYZ";
Permutations(str);
return 0;
}
|
Output
XYZ
XZY
YXZ
YZX
ZXY
ZYX
87. Write a Program to Remove Brackets From an Algebraic Expression
C++
#include <iostream>
#include <string>
using namespace std;
string remove_brackets(string str)
{
string result = "";
for (char c : str) {
if (c != '(' && c != ')') {
result += c;
}
}
return result;
}
int main()
{
string str = "Geeks)(for)(geeks";
cout << "Without brackets: " << remove_brackets(str)
<< endl;
return 0;
}
|
88. Program to Perform Insert, Delete, and Print Operations Singly Linked List
C++
#include <iostream>
using namespace std;
struct Node {
int data;
Node* next;
};
Node* head = nullptr;
void insert(int data)
{
Node* newNode = new Node();
newNode->data = data;
newNode->next = head;
head = newNode;
}
void deleteNode(int data)
{
Node *temp = head, *prev = nullptr;
if (temp != nullptr && temp->data == data) {
head = temp->next;
delete temp;
return;
}
while (temp != nullptr && temp->data != data) {
prev = temp;
temp = temp->next;
}
if (temp == nullptr)
return;
prev->next = temp->next;
delete temp;
}
void printList()
{
Node* temp = head;
while (temp != nullptr) {
cout << temp->data << " ";
temp = temp->next;
}
cout << endl;
}
int main()
{
insert(1);
insert(2);
insert(3);
insert(4);
insert(5);
cout << "Linked List is \n";
printList();
deleteNode(3);
cout << "Linked List after deletion of 3: ";
printList();
return 0;
}
|
Output
Linked List is
5 4 3 2 1
Linked List after deletion of 3: 5 4 2 1
89. Program to Perform Insert, Delete, and Print Operations Doubly Linked List
C++
#include <iostream>
using namespace std;
struct Node {
int data;
Node* next;
Node* prev;
};
class DoublyLinkedList {
private:
Node* head;
public:
DoublyLinkedList()
: head(NULL)
{
}
void insertAtStart(int data)
{
Node* newNode = new Node;
newNode->data = data;
newNode->next = head;
newNode->prev = NULL;
if (head != NULL)
head->prev = newNode;
head = newNode;
}
void deleteNode(int data)
{
Node* temp = head;
while (temp != NULL && temp->data != data)
temp = temp->next;
if (temp == NULL)
return;
if (temp->prev != NULL)
temp->prev->next = temp->next;
else
head = temp->next;
if (temp->next != NULL)
temp->next->prev = temp->prev;
delete temp;
}
void printList()
{
Node* temp = head;
while (temp != NULL) {
std::cout << temp->data << " ";
temp = temp->next;
}
std::cout << std::endl;
}
};
int main()
{
DoublyLinkedList dll;
dll.insertAtStart(1);
dll.insertAtStart(2);
dll.insertAtStart(3);
dll.insertAtStart(4);
dll.insertAtStart(5);
std::cout << "Original Doubly Linked List: ";
dll.printList();
dll.deleteNode(2);
std::cout << "Doubly Linked List after deletion: ";
dll.printList();
return 0;
}
|
Output
Original Doubly Linked List: 5 4 3 2 1
Doubly Linked List after deletion: 5 4 3 1
90. Program to Perform Insert, Delete, and Print Operations Circular Linked List
C++
#include <iostream>
struct Node {
int data;
Node* next;
};
class CircularLinkedList {
private:
Node* head;
public:
CircularLinkedList()
: head(NULL)
{
}
void insertAtStart(int data)
{
Node* newNode = new Node;
newNode->data = data;
newNode->next = head;
if (head == NULL) {
head = newNode;
newNode->next = head;
}
else {
Node* temp = head;
while (temp->next != head)
temp = temp->next;
temp->next = newNode;
head = newNode;
}
}
void deleteNode(int data)
{
Node* temp = head;
if (temp == NULL)
return;
if (temp->next == head) {
head = NULL;
delete temp;
return;
}
Node* prev = NULL;
while (temp->next != head && temp->data != data) {
prev = temp;
temp = temp->next;
}
if (temp->data != data)
return;
prev->next = temp->next;
if (temp == head)
head = temp->next;
delete temp;
}
void printList()
{
Node* temp = head;
while (temp->next != head) {
std::cout << temp->data << " ";
temp = temp->next;
}
std::cout << temp->data << std::endl;
}
};
int main()
{
CircularLinkedList cll;
cll.insertAtStart(1);
cll.insertAtStart(2);
cll.insertAtStart(3);
cll.insertAtStart(4);
cll.insertAtStart(5);
std::cout << "Original Circular Linked list ";
cll.printList();
cll.deleteNode(2);
std::cout << "Circular Linked List after deletion ";
cll.printList();
return 0;
}
|
Output
Original Circular Linked list 5 4 3 2 1
Circular Linked List after deletion 5 4 3 1
91. Program for Inorder Traversal in a Binary Tree
C++
#include <bits/stdc++.h>
using namespace std;
struct Node {
int data;
struct Node *left, *right;
};
Node* newNode(int data)
{
Node* temp = new Node;
temp->data = data;
temp->left = temp->right = NULL;
return temp;
}
void printInorder(struct Node* node)
{
if (node == NULL)
return;
printInorder(node->left);
cout << node->data << " ";
printInorder(node->right);
}
int main()
{
struct Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->left->right = newNode(5);
cout << "Inorder traversal of binary tree is \n";
printInorder(root);
return 0;
}
|
Output
Inorder traversal of binary tree is
4 2 5 1 3
92. Program to Find All its Subsets From a Set of Positive Integers
C++
#include <bits/stdc++.h>
using namespace std;
void find_subset(vector<int>& A, vector<vector<int> >& ans,
vector<int>& subset, int index)
{
ans.push_back(subset);
for (int i = index; i < A.size(); i++) {
subset.push_back(A[i]);
find_subset(A, ans, subset, i + 1);
subset.pop_back();
}
return;
}
vector<vector<int> > subsets(vector<int>& A)
{
vector<int> subset;
vector<vector<int> > ans;
int index = 0;
find_subset(A, ans, subset, index);
return ans;
}
int main()
{
vector<int> array = { 1, 2, 3, 4, 5 };
vector<vector<int> > ans = subsets(array);
for (int i = 0; i < ans.size(); i++) {
for (int j = 0; j < ans[i].size(); j++)
cout << ans[i][j] << " ";
cout << endl;
}
return 0;
}
|
Output
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 5
1 2 4
1 2 4 5
1 2 5
1 3
1 3 4
1 3 4 5
1 3 5
1 4
1 4 5
1 5
2
2 3
2 3 4
2 3 4 5
2 3 5
2 4
2 4 5
2 5
3
3 4
3 4 5
3 5
4
4 5
5
93. Program for Preorder Traversal in a Binary Tree
C++
#include <bits/stdc++.h>
using namespace std;
struct Node {
int data;
struct Node *left, *right;
};
Node* newNode(int data)
{
Node* temp = new Node;
temp->data = data;
temp->left = temp->right = NULL;
return temp;
}
void printPreorder(struct Node* node)
{
if (node == NULL)
return;
cout << node->data << " ";
printPreorder(node->left);
printPreorder(node->right);
}
int main()
{
struct Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->left->right = newNode(5);
cout << "Preorder traversal of binary tree is \n";
printPreorder(root);
return 0;
}
|
Output
Preorder traversal of binary tree is
1 2 4 5 3
94. Program for Postorder Traversal in a Binary Tree
C++
#include <bits/stdc++.h>
using namespace std;
struct Node {
int data;
struct Node *left, *right;
};
Node* newNode(int data)
{
Node* temp = new Node;
temp->data = data;
temp->left = temp->right = NULL;
return temp;
}
void printPostorder(struct Node* node)
{
if (node == NULL)
return;
printPostorder(node->left);
printPostorder(node->right);
cout << node->data << " ";
}
int main()
{
struct Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->left->right = newNode(5);
cout << "Postorder traversal of binary tree is \n";
printPostorder(root);
return 0;
}
|
Output
Postorder traversal of binary tree is
4 5 2 3 1
95. Program for Level-Order Traversal in a Binary Tree
C++
#include <bits/stdc++.h>
using namespace std;
struct Node {
int data;
struct Node *left, *right;
};
Node* newNode(int data)
{
Node* temp = new Node;
temp->data = data;
temp->left = temp->right = NULL;
return temp;
}
void printLevelOrder(struct Node* node)
{
if (node == NULL)
return;
queue<struct Node*> q;
while (node) {
if (node->left) {
q.push(node->left);
}
if (node->right) {
q.push(node->right);
}
cout << node->data << " ";
node = q.front();
q.pop();
}
}
int main()
{
struct Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->left->right = newNode(5);
cout << "Levelorder traversal of binary tree is \n";
printLevelOrder(root);
return 0;
}
|
Output
Levelorder traversal of binary tree is
1 2 3 4 5
96. Write a Program for the Top View of a Binary Tree
C++
#include <bits/stdc++.h>
using namespace std;
struct Node {
Node* left;
Node* right;
int hd;
int data;
};
Node* newNode(int key)
{
Node* node = new Node();
node->left = node->right = NULL;
node->data = key;
return node;
}
void topView(Node* root)
{
if (root == NULL) {
return;
}
queue<Node*> q;
map<int, int> m;
int hd = 0;
root->hd = hd;
q.push(root);
while (q.size()) {
hd = root->hd;
if (m.count(hd) == 0)
m[hd] = root->data;
if (root->left) {
root->left->hd = hd - 1;
q.push(root->left);
}
if (root->right) {
root->right->hd = hd + 1;
q.push(root->right);
}
q.pop();
root = q.front();
}
for (auto i = m.begin(); i != m.end(); i++) {
cout << i->second << " ";
}
}
int main()
{
Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->right->right = newNode(5);
topView(root);
return 0;
}
|
97. Write a Program to Print the Bottom View of a Binary Tree
C++
#include <bits/stdc++.h>
using namespace std;
struct Node {
Node* left;
Node* right;
int data;
int hd;
};
Node* newNode(int key)
{
Node* node = new Node();
node->data = key;
node->left = node->right = NULL;
node->hd = 0;
return node;
}
void bottomView(Node* root)
{
if (root == NULL)
return;
queue<Node*> q;
map<int, int> m;
int hd = 0;
root->hd = hd;
q.push(root);
while (!q.empty()) {
Node* temp = q.front();
q.pop();
hd = temp->hd;
m[hd] = temp->data;
if (temp->left != NULL) {
temp->left->hd = hd - 1;
q.push(temp->left);
}
if (temp->right != NULL) {
temp->right->hd = hd + 1;
q.push(temp->right);
}
}
for (auto i = m.begin(); i != m.end(); ++i)
cout << i->second << " ";
}
int main()
{
Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->right->right = newNode(5);
bottomView(root);
return 0;
}
|
98. Write a Program to Print the Left View of a Binary Tree
C++
#include <bits/stdc++.h>
using namespace std;
struct Node {
Node* left;
Node* right;
int data;
};
Node* newNode(int key)
{
Node* node = new Node;
node->data = key;
node->left = node->right = NULL;
return node;
}
void leftView(Node* root)
{
if (!root) {
return;
}
queue<Node*> q;
q.push(root);
while (!q.empty()) {
int n = q.size();
for (int i = 1; i <= n; i++) {
Node* temp = q.front();
q.pop();
if (i == 1)
cout << temp->data << " ";
if (temp->left != NULL)
q.push(temp->left);
if (temp->right != NULL)
q.push(temp->right);
}
}
}
int main()
{
Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->right->right = newNode(5);
leftView(root);
}
|
99. Write a Program to Print the Right View of the Binary Tree
C++
#include <bits/stdc++.h>
using namespace std;
struct Node {
Node* left;
Node* right;
int data;
};
Node* newNode(int key)
{
Node* node = new Node;
node->data = key;
node->left = node->right = NULL;
return node;
}
void rightView(Node* root)
{
if (root == NULL) {
return;
}
queue<Node*> q;
q.push(root);
while (!q.empty()) {
int n = q.size();
while (n--) {
Node* x = q.front();
q.pop();
if (n == 0) {
cout << x->data << " ";
}
if (x->left) {
q.push(x->left);
}
if (x->right) {
q.push(x->right);
}
}
}
}
int main()
{
Node* root = newNode(1);
root->left = newNode(2);
root->right = newNode(3);
root->left->left = newNode(4);
root->right->right = newNode(5);
rightView(root);
}
|
100. Write a Program for the Conversion of Infix Expression to Postfix Expression
C++
#include <bits/stdc++.h>
using namespace std;
string infixToPostfix(string& expression)
{
string postfix;
stack<char> ope_stack;
unordered_map<char, int> pre = { { '+', 1 },
{ '-', 1 },
{ '*', 2 },
{ '/', 2 },
{ '(', 0 } };
int length = expression.length();
for (int i = 0; i < length; i++) {
char c = expression[i];
if ((c >= 92 && c <= 122) || (c >= 48 && c <= 57)) {
postfix.push_back(c);
}
else if (c == '(') {
ope_stack.push(c);
}
else if (c == ')') {
while (ope_stack.top() != '(') {
postfix.push_back(ope_stack.top());
ope_stack.pop();
}
ope_stack.pop();
}
else {
while (!ope_stack.empty()
&& pre.at(c) < pre.at(ope_stack.top())) {
postfix.push_back(ope_stack.top());
ope_stack.pop();
}
ope_stack.push(c);
}
}
while (!ope_stack.empty()) {
postfix.push_back(ope_stack.top());
ope_stack.pop();
}
return postfix;
}
int main()
{
string s = "a*b+(c-d)";
cout << infixToPostfix(s);
return 0;
}
|
Conclusion
Coding interviews can be challenging task, but they are also a great opportunity to test your skills and knowledge. By practicing with commonly ask C++ coding interview questions, you can increase your chances of success.
Remember to stay calm, communicate your thought process clearly, and don’t be afraid to ask for clarification if needed. With hard work and preparation, you can ace your interview and land your dream job!
C++ Coding Interview Questions – FAQs
Q: What are the most common C++ coding interview questions?
The most common C++ coding interview questions are designed to test your knowledge of the following topics:
- C++ syntax and semantics
- Data structures and algorithms
- Object-oriented programming
- Memory management
- Pointers
- Templates & More.
Q: What should I do during a C++ coding interview?
When you are asked a coding question in an interview, take a moment to think about the problem before you start coding. Explain your thought process to the interviewer as you are coding. This will help them to understand your approach to solving problems.
Q: What are some tips for writing clean and efficient code?
Here are some tips for writing clean and efficient code:
- Use meaningful variable names.
- Use whitespace to make your code readable.
- Break down complex problems into smaller, more manageable problems.
- Use comments to explain your code.
- Test your code thoroughly.
- Use appropriate data structures and algorithms.
- Avoid unnecessary duplication of code.
Q: How can I improve my communication skills during C++ coding interviews?
Here are some tips for improving your communication skills during C++ coding interviews:
- Speak clearly and concisely.
- Explain your thought process to the interviewer.
- Ask clarifying questions if needed.
- Be prepared to answer questions about your code.
- Be open to feedback.
Practicing explaining your code to others is a great way to improve your communication skills. You can also practice by giving yourself mock interviews.
Like Article
Suggest improvement
Share your thoughts in the comments
Please Login to comment...