HackerEarth String Clash problem solution

In this HackerEarth String Clash problem solution, you are given two strings S and T of equal lengths. You need to pick some characters from the first string, some from the second string, and then form a new string by rearranging the characters you have picked. You need to find the length of the maximum string that you can make which will be a palindrome.

HackerEarth String Clash problem solution.

#include<bits/stdc++.h>
#define LL long long int
#define M 1000000007
#define endl "\n"
#define eps 0.00000001
LL pow(LL a,LL b,LL m){LL x=1,y=a;while(b > 0){if(b%2 == 1){x=(x*y);if(x>m) x%=m;}y = (y*y);if(y>m) y%=m;b /= 2;}return x%m;}
LL gcd(LL a,LL b){if(b==0) return a; else return gcd(b,a%b);}
LL gen(LL start,LL end){LL diff = end-start;LL temp = rand()%start;return temp+diff;}
using namespace std;
int f[1000001];
int main()  {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int ans = 0;
  string a , b;
  cin >> a >> b;
  for(int i = 0; i < a.length(); i++) {
    f[a[i] - 'a']++;
  }
  for(int i = 0; i < b.length(); i++) {
    f[b[i] - 'a']++;
  }
  bool flag = 0;
  for(int i = 0; i < 26; i++) {
    ans = ans + f[i] - (f[i] % 2);
    if(f[i] % 2)  {
      flag = 1;
    }
  }
  cout << ans + flag;
}

Second solution

#include <bits/stdc++.h>

using namespace std;

vector<int> f(26, 0);

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    string s, t;
    cin >> s >> t;
    int n = s.size();
    for(int i = 0; i < n; i ++)
        f[s[i] - 'a'] ++;
    for(int i = 0; i < n; i ++)
        f[t[i] - 'a'] ++;
    bool odd = 0;
    int total_len = 0;
    for(int i = 0; i < 26; i ++) {
        if(f[i] & 1) {
            odd = 1;
            f[i] --;
        }
        total_len += f[i];
    }
    if(odd)
        total_len ++;
    cout << total_len;
    return 0;
}