Find one extra character in a string

Given two strings which are of lengths n and n+1. The second string contains all the character of the first string, but there is one extra character. Your task to find the extra character in the second string.

Examples :

Input : string strA = "abcd";
        string strB = "cbdae";
Output : e
string B contain all the element 
there is a one extra character which is e

Input : string strA = "kxml";
        string strB = "klxml";
Output : l
string B contain all the element 
there is a one extra character which is l

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Method 1(Brute Force):-
Check with two for loop.
Time Complexity:- O(n^2)
Space Complexity:- O(1).

Method 2(Hash Map):-
Create an empty hash table and insert all character of second string. Now remove all characters of first string. Remaining character is the extra character.

Time Complexity:- O(n)
Auxiliary Space:- O(n).

C++

// CPP program to find extra character in one  
// string 
#include <bits/stdc++.h> 
using namespace std; 
  
char findExtraCharcter(string strA, string strB) 
{ 
    // store string values in map 
    unordered_map<char, int> m1; 
  
    // store second string in map with frequency 
    for (int i = 0; i < strB.length(); i++) 
        m1[strB[i]]++; 
  
    // store first string in map with frequency 
    for (int i = 0; i < strA.length(); i++) 
        m1[strA[i]]--; 
  
    for (auto h1 = m1.begin(); h1 != m1.end(); h1++) { 
  
        // if the frequency is 1 then this 
        // character is which is added extra 
        if (h1->second == 1) 
            return h1->first; 
    } 
} 
  
int main() 
{ 
    // given string 
    string strA = "abcd"; 
    string strB = "cbdad"; 
  
    // find Extra Character 
    cout << findExtraCharcter(strA, strB); 
} 

Java

// Java program to find extra character in one  
// string 
class GFG  
{ 
  
static char findExtraCharcter(char []strA, char[] strB) 
{ 
    // store string values in map 
    int[] m1 = new int[256]; 
  
    // store second string in map with frequency 
    for (int i = 0; i < strB.length; i++) 
        m1[strB[i]]++; 
  
    // store first string in map with frequency 
    for (int i = 0; i < strA.length; i++) 
        m1[strA[i]]--; 
  
    for (int i=0;i<m1.length;i++) 
    { 
  
        // if the frequency is 1 then this 
        // character is which is added extra 
        if (m1[i]== 1) 
            return (char) i; 
    } 
    return Character.MIN_VALUE; 
} 
  
// Driver code 
public static void main(String[] args)  
{ 
    // given string 
    String strA = "abcd"; 
    String strB = "cbdad"; 
  
    // find Extra Character 
    System.out.println(findExtraCharcter(strA.toCharArray(), strB.toCharArray())); 
    } 
} 
  
// This code is contributed by 29AjayKumar 

Python3

# Python3 program to find extra character  
# in one string 
def findExtraCharacter(strA, strB): 
  
    # store string values in map 
    m1 = {} 
  
    # store second string in map  
    # with frequency 
    for i in strB: 
        if i in m1: 
            m1[i] += 1
        else: 
            m1[i] = 1
  
    # store first string in map  
    # with frequency 
    for i in strA: 
        m1[i] -= 1
  
    for h1 in m1: 
  
        # if the frequency is 1 then this 
        # character is which is added extra 
        if m1[h1] == 1: 
            return h1 
  
# Driver Code 
if __name__ == "__main__": 
  
    # given string 
    strA = 'abcd'
    strB = 'cbdad'
  
    # find Extra Character 
    print(findExtraCharacter(strA, strB)) 
  
# This code is contributed by 
# sanjeev2552 

C#

// C# program to find extra character in one  
// string 
using System; 
      
class GFG  
{ 
  
static char findExtraCharcter(char []strA, char[] strB) 
{ 
    // store string values in map 
    int[] m1 = new int[256]; 
  
    // store second string in map with frequency 
    for (int i = 0; i < strB.Length; i++) 
        m1[strB[i]]++; 
  
    // store first string in map with frequency 
    for (int i = 0; i < strA.Length; i++) 
        m1[strA[i]]--; 
  
    for (int i = 0; i < m1.Length; i++) 
    { 
  
        // if the frequency is 1 then this 
        // character is which is added extra 
        if (m1[i]== 1) 
            return (char) i; 
    } 
    return char.MinValue; 
} 
  
// Driver code 
public static void Main(String[] args)  
{ 
    // given string 
    String strA = "abcd"; 
    String strB = "cbdad"; 
  
    // find Extra Character 
    Console.WriteLine(findExtraCharcter(strA.ToCharArray(),  
                                        strB.ToCharArray())); 
    } 
} 
  
// This code is contributed by Rajput-Ji 

Output:

Method 3(Bits):-
traverse first and second string from starting with xor operation at the end you get the character which is extra.
Time Complexity:- O(n+n+1)
Space Complexity:- O(1).

C++

// CPP program to find extra character in one  
// string 
#include <iostream> 
using namespace std; 
  
char findExtraCharcter(string strA, string strB) 
{ 
    // result store the result 
    int res = 0, i; 
  
    // traverse string A till end and  
    // xor with res 
    for (i = 0; i < strA.length(); i++) { 
  
        // xor with res 
        res ^= strA[i]; 
    } 
  
    // traverse string B till end and  
    // xor with res 
    for (i = 0; i < strB.length(); i++) { 
  
        // xor with res 
        res ^= strB[i]; 
    } 
  
    // print result at the end 
    return ((char)(res)); 
} 
  
int main() 
{ 
    // given string 
    string strA = "abcd"; 
    string strB = "cbdad"; 
    cout << findExtraCharcter(strA, strB); 
    return 0; 
} 

Java

// Java program to find extra 
// character in one string 
import java.io.*; 
  
class GFG { 
      
    static char findExtraCharcter(String strA, 
                                  String strB) 
    { 
        // result store the result 
        int res = 0, i; 
      
        // traverse string A till  
        // end and xor with res 
        for (i = 0; i < strA.length(); i++) 
        { 
            // xor with res 
            res ^= strA.charAt(i); 
        } 
      
        // traverse string B till end and  
        // xor with res 
        for (i = 0; i < strB.length(); i++) 
        { 
            // xor with res 
            res ^= strB.charAt(i); 
        } 
      
        // print result at the end 
        return ((char)(res)); 
    } 
      
    // Driver code 
    public static void main(String args[]) 
    { 
        // given string 
        String strA = "abcd"; 
        String strB = "cbdad"; 
        System.out.println(findExtraCharcter(strA, strB)); 
    } 
} 
  
/*This code is contributed by Nikita Tiwari.*/

Python 3

# Python 3 program to find  
# extra character in one string 
  
def findExtraCharcter(strA, strB) : 
      
    # result store the result 
    res = 0
  
    # traverse string A till  
    # end and xor with res 
    for i in range(0,len(strA)) : 
          
        # xor with res 
        res =res ^ (ord)(strA[i]) 
          
    # traverse string B till  
    # end and xor with res 
    for i in range(0,len(strB)) : 
          
        # xor with res 
        res = res ^ (ord)(strB[i]) 
          
    # print result at the end 
    return ((chr)(res)); 
  
# given string 
strA = "abcd"
strB = "cbdad"
print(findExtraCharcter(strA, strB)) 
  
# This code is contributed by Nikita Tiwari. 

C#

// C# program to find extra character 
// in one string 
using System; 
  
class GFG { 
  
    static char findExtraCharcter(string strA,  
                                  string strB) 
    { 
        // result store the result 
        int res = 0, i; 
      
        // traverse string A till end and  
        // xor with res 
        for (i = 0; i < strA.Length; i++) { 
      
            // xor with res 
            res ^= strA[i]; 
        } 
      
        // traverse string B till end and  
        // xor with res 
        for (i = 0; i < strB.Length; i++) { 
      
            // xor with res 
            res ^= strB[i]; 
        } 
      
        // print result at the end 
        return ((char)(res)); 
    } 
      
    // Driver Code 
    public static void Main() 
    { 
        // given string 
        string strA = "abcd"; 
        string strB = "cbdad"; 
        Console.WriteLine( 
            findExtraCharcter(strA, strB)); 
    } 
} 
  
// This code is contributed by Manish Shaw  
// (manishshaw1) 

PHP

<?php 
// PHP program to find extra character in 
// one string 
  
function findExtraCharcter($strA, $strB) 
{ 
    // result store the result 
    $res = 0; 
  
    // traverse string A till end and  
    // xor with res 
    for ($i = 0; $i < strlen($strA); $i++) 
    { 
  
        // xor with res 
        $res ^= ord($strA[$i]); 
    } 
  
    // traverse string B till end and  
    // xor with res 
    for ($i = 0; $i < strlen($strB); $i++) 
    { 
  
        // xor with res 
        $res ^= ord($strB[$i]); 
    } 
  
    // print result at the end 
    return $res; 
} 
  
// Driver code 
$strA = "abcd"; 
$strB = "cbdad"; 
echo chr(findExtraCharcter($strA, $strB)); 
  
// This code is contributed by Manish Shaw 
// (manishshaw1) 
?> 

Output:

Method 4(Character Code):-
Add the character codes of both the strings. Minus character codes of smaller string from larger string and convert the result integer into character.

Time Complexity:- O(n)
Auxiliary Space:- O(1).

C++

    // C++ program to find extra 
// character in one string 
#include<bits/stdc++.h> 
using namespace std; 
  
char findExtraCharacter(string s1, string s2) 
{      
    string smallStr; 
    string largeStr; 
  
    // Determine string with extra character. 
    if(s1.size() > s2.size())  
    { 
        smallStr = s2; 
        largeStr = s1; 
    }  
    else
    { 
        smallStr = s1; 
        largeStr = s2; 
    } 
  
    int smallStrCodeTotal = 0; 
    int largeStrCodeTotal = 0; 
    int i = 0; 
  
    // Add character codes of both the strings 
    for(; i < smallStr.size(); i++)  
    { 
        smallStrCodeTotal += smallStr[i]; 
        largeStrCodeTotal += largeStr[i]; 
    } 
  
    // Add last character code of large string. 
    largeStrCodeTotal += largeStr[i]; 
  
    // Minus the character code of smaller string from  
    // the character code of large string.  
    // The result will be the extra character code. 
    int intChar = largeStrCodeTotal - smallStrCodeTotal;      
    return (char)intChar; 
} 
  
// Driver code  
int main() 
{ 
    string s1 = "abcd"; 
    string s2 = "cbdae"; 
      
    char extraChar = findExtraCharacter(s1, s2); 
    cout<<"Extra character: " <<(extraChar)<<endl; 
    return 0; 
} 
  
// This code is contributed by Princi Singh 

Java

// Java program to find extra 
// character in one string 
  
public class Test { 
  
    private static char findExtraCharacter(String s1, String s2) {         
        String smallStr; 
        String largeStr; 
  
        // Determine String with extra character. 
        if(s1.length() > s2.length()) { 
            smallStr = s2; 
            largeStr = s1; 
        } else { 
            smallStr = s1; 
            largeStr = s2; 
        } 
  
        int smallStrCodeTotal = 0; 
        int largeStrCodeTotal = 0; 
        int i = 0; 
  
        // Add character codes of both the strings 
        for(; i < smallStr.length(); i++) { 
            smallStrCodeTotal += smallStr.charAt(i); 
            largeStrCodeTotal += largeStr.charAt(i); 
        } 
  
        // Add last character code of large String. 
        largeStrCodeTotal += largeStr.charAt(i); 
  
        // Minus the character code of smaller string from  
        // the character code of large string.  
        // The result will be the extra character code. 
        int intChar = largeStrCodeTotal - smallStrCodeTotal;         
        return (char)intChar; 
    } 
      
    public static void main(String[] args) { 
        String s1 = "abcd"; 
        String s2 = "cbdae"; 
          
        char extraChar = findExtraCharacter(s1, s2); 
        System.out.println("Extra character: " + extraChar); 
          
    } 
} 
  
  
/*This code is contributed by Amol Bhosale.*/

Python3

# Python Program to find extra character in one string  
def findExtraCharacter(s1,s2): 
    smallStr = "" 
    largeStr = "" 
      
    # Determine string with extra character 
    if(len(s1) > len(s2)): 
        smallStr = s2 
        largeStr = s1 
    else: 
        smallStr = s1 
        largeStr = s2 
    smallStrCodeTotal = 0
    largeStrCodeTotal = 0
    i = 0
      
    # Add Character codes of both the strings 
    while(i < len(smallStr)): 
        smallStrCodeTotal += ord(smallStr[i]) 
        largeStrCodeTotal += ord(largeStr[i]) 
        i += 1
      
    # Add last character code of large string 
    largeStrCodeTotal += ord(largeStr[i]) 
      
    # Minus the character code of smaller string  
    # from the character code of large string 
    # The result will be the extra character code 
    intChar = largeStrCodeTotal - smallStrCodeTotal 
    return chr(intChar) 
  
# Driver code 
s1 = "abcd"
s2 = "cbdae"
extraChar = findExtraCharacter(s1, s2) 
print("Extra Character:", extraChar) 
  
# This code is contributed by simranjenny84 

C#

// C# program to find extra  
// character in one string  
using System; 
  
class GFG  
{  
    private static char findExtraCharacter(String s1,  
                                           String s2)  
    {      
        String smallStr;  
        String largeStr;  
  
        // Determine String with extra character.  
        if(s1.Length > s2.Length)  
        {  
            smallStr = s2;  
            largeStr = s1;  
        }  
        else 
        {  
            smallStr = s1;  
            largeStr = s2;  
        }  
  
        int smallStrCodeTotal = 0;  
        int largeStrCodeTotal = 0;  
        int i = 0;  
  
        // Add character codes of both the strings  
        for(; i < smallStr.Length; i++)  
        {  
            smallStrCodeTotal += smallStr[i];  
            largeStrCodeTotal += largeStr[i];  
        }  
  
        // Add last character code of large String.  
        largeStrCodeTotal += largeStr[i];  
  
        // Minus the character code of smaller string  
        // from the character code of large string.  
        // The result will be the extra character code.  
        int intChar = largeStrCodeTotal -  
                      smallStrCodeTotal;          
        return (char)intChar;  
    }  
      
    public static void Main(String[] args) 
    {  
        String s1 = "abcd";  
        String s2 = "cbdae";  
          
        char extraChar = findExtraCharacter(s1, s2);  
        Console.WriteLine("Extra character: " +  
                                    extraChar);  
    }  
}  
  
// This code is contributed by PrinciRaj1992 

Output:

Extra character: e

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.

My Personal Notes

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

Java

Python3

C#

C++

Java

Python 3

C#

PHP

C++

Java

Python3

C#

Recommended Posts: