Common characters in n strings
Given n strings, find the common characters in all the strings. In simple words, find characters that appear in all the strings and display them in alphabetical order or lexicographical order.
Note* we’ll be considering that the strings contain lower case letters only.
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Examples:
Input : geeksforgeeks
gemkstones
acknowledges
aguelikes
Output : e g k s
Input : apple
orange
Output : a e
We’ll use two hash arrays of size 26 (for a-z, where 0 is a, and z is 25).
The approach will be simple, if we have seen a character before we’ll mark it and if we haven’t then ignore the character because it is not a common one.
Psuedocode :
commonCharacters :
for i= 0 to n-1:
// here m is length of ith string
for j = 0 to m-1:
if ( character seen before ) :
mark the character
else :
ignore it
display all the marked characters
C++
// CPP Program to find all the common characters// in n strings#include <bits/stdc++.h>using namespace std; const int MAX_CHAR = 26; void commonCharacters(string str[], int n){ // primary array for common characters // we assume all characters are seen before. bool prim[MAX_CHAR]; memset(prim, true, sizeof(prim)); // for each string for (int i = 0; i < n; i++) { // secondary array for common characters // Initially marked false bool sec[MAX_CHAR] = { false }; // for every character of ith string for (int j = 0; str[i][j]; j++) { // if character is present in all // strings before, mark it. if (prim[str[i][j] - 'a']) sec[str[i][j] - 'a'] = true; } // copy whole secondary array into primary memcpy(prim, sec, MAX_CHAR); } // displaying common characters for (int i = 0; i < 26; i++) if (prim[i]) printf("%c ", i + 'a');} // Driver's Codeint main(){ string str[] = { "geeksforgeeks", "gemkstones", "acknowledges", "aguelikes" }; int n = sizeof(str)/sizeof(str[0]); commonCharacters(str, n); return 0;} |
Java
// Java Program to find all the common characters// in n stringsimport java.util.*;import java.lang.*; class GFG { static int MAX_CHAR = 26; public static void commonCharacters(String str[], int n) { // primary array for common characters // we assume all characters are seen before. Boolean[] prim = new Boolean[MAX_CHAR]; Arrays.fill(prim, new Boolean(true)); // for each string for (int i = 0; i < n; i++) { // secondary array for common characters // Initially marked false Boolean[] sec = new Boolean[MAX_CHAR]; Arrays.fill(sec, new Boolean(false)); // for every character of ith string for (int j = 0; j < str[i].length(); j++) { // if character is present in all // strings before, mark it. if (prim[str[i].charAt(j) - 'a']) sec[str[i].charAt(j) - 'a'] = true; } // copy whole secondary array into primary System.arraycopy(sec, 0, prim, 0, MAX_CHAR); } // displaying common characters for (int i = 0; i < 26; i++) if (prim[i]){ System.out.print(Character.toChars(i + 97)); System.out.print(" "); } } // Driver code public static void main(String[] args) { String str[] = { "geeksforgeeks", "gemkstones", "acknowledges", "aguelikes" }; int n = str.length; commonCharacters(str, n); }} // This code is contributed by Prasad Kshirsagar |
Python3
# Python3 Program to find all the # common characters in n stringsMAX_CHAR = 26 def commonCharacters(strings, n) : # primary array for common characters # we assume all characters are seen before. prim = [True] * MAX_CHAR # for each strings for i in range(n): # secondary array for common characters # Initially marked false sec = [False] * MAX_CHAR # for every character of ith strings for j in range(len(strings[i])): # if character is present in all # strings before, mark it. if (prim[ord(strings[i][j]) - ord('a')]) : sec[ord(strings[i][j]) - ord('a')] = True # copy whole secondary array # into primary for i in range(MAX_CHAR): prim[i] = sec[i] # displaying common characters for i in range(26): if (prim[i]) : print("%c " % (i + ord('a')), end = "") # Driver's Code strings = [ "geeksforgeeks", "gemkstones", "acknowledges", "aguelikes" ]n = len(strings)commonCharacters(strings, n) # This code is contributed by Niwesh Gupta |
C#
// C# Program to find all the // common characters in n stringsusing System; class GFG { static int MAX_CHAR = 26; public static void commonCharacters(String []str, int n) { // primary array for common characters // we assume all characters are seen before. Boolean[] prim = new Boolean[MAX_CHAR]; for(int i = 0; i < prim.Length; i++) prim[i] = true; // for each string for (int i = 0; i < n; i++) { // secondary array for common characters // Initially marked false Boolean[] sec = new Boolean[MAX_CHAR]; for(int s = 0; s < sec.Length; s++) sec[s]=false; // for every character of ith string for (int j = 0; j < str[i].Length; j++) { // if character is present in all // strings before, mark it. if (prim[str[i][j] - 'a']) sec[str[i][j] - 'a'] = true; } // Copy whole secondary array into primary Array.Copy(sec, 0, prim, 0, MAX_CHAR); } // Displaying common characters for (int i = 0; i < 26; i++) if (prim[i]) { Console.Write((char)(i + 97)); Console.Write(" "); } } // Driver code public static void Main(String[] args) { String []str = { "geeksforgeeks", "gemkstones", "acknowledges", "aguelikes" }; int n = str.Length; commonCharacters(str, n); }} // This code is contributed by Rajput-JI |
Output:
e g k s
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