hackerearth_magical_word.cpp

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

int main()
{
   int prime[] = {67,71,73,79,83,89,97,101,103,107,109,113}; 
    int t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        string s;
        cin>>s;
        int len = s.length();
        for(int i=0;i<len;i++){
            int j=0;
            while(int(s[i])>=prime[j]) j++;
            if(int(s[i])<= 67) cout<<char(67);
            else if(int(s[i])>=113) cout<<char(113);
            else {
                int a = int(s[i]) - prime[j-1];
                int b = prime[j] - int(s[i]);
                if(a<=b) cout<<char(prime[j-1]);
                else cout<<char(prime[j]);
            }
        }
        cout<<"\n";
    }
    return 0;
}