remove_common_character.cpp

#include <bits/stdc++.h> 
using namespace std; 

string concatenetedString(string s1, string s2) 
{ 
    string res = ""; // result 

    // store all characters of s2 in map 

    unordered_map<char, int> m; 

    for (int i = 0; i < s2.size(); i++) 

        m[s2[i]] = 1; 
        
    // Find characters of s1 that are not 

    // present in s2 and append to result 

    for (int i = 0; i < s1.size(); i++) { 

        if (m.find(s1[i]) == m.end()) 

            res += s1[i]; 

        else

            m[s1[i]] = 2; 

    } 

    // Find characters of s2 that are not 

    // present in s1. 

    for (int i = 0; i < s2.size(); i++) 

        if (m[s2[i]] == 1) 

            res += s2[i]; 

    return res; 
} 

/* Driver program */
int main() 
{ 

    string s1 = "abcd"; 

    string s2 = "cdefg"; 

    cout << concatenetedString(s1, s2); 

    return 0; 
} 
/*abefg*/