Problem:746B -Decoding

• language:C++
• status: accepted

#include<iostream>
#include<bits/stdc++.h>

using namespace std;
string reverse (string input){  
    string rev;
    for (int i=input.length()-1;i>=0;i--){
        rev+=input[i];
    }
    return rev;
}

string solve(){
    int n;
    cin>>n;
    string s;
    cin>>s;
    string  a; //last
    string b;  //first
    
if(n%2==0){  for(int i=n-1;i>=0;i--)
{
  if(i%2==0) a=a+s[i];
  else b=b+s[i];
}}
else{
      for(int i=n-1;i>=0;i--)
{
  if(i%2==0) b=b+s[i];
  else a=a+s[i];
}
}
// cout<<a<<endl;
// cout<<b<<endl;
cout<<   a+reverse(b);
}


int main(){
    solve();
}

I was solving the following problem @ 479A — Expression

I feel that the given test case had a wrong output.

Test: #8, time: 0 ms., memory: 0 KB, exit code: 0, checker exit code: 1, verdict: WRONG_ANSWER

Input 6 7 1 Output 49 Answer 48