Please provide hint for this problem ( please help ! )

general
1

https://mycode.prepbytes.com/problems/strings/ALIENFRIEND

My approach :-

  1. find total ‘?’ in left side and store it in left

  2. find total ‘?’ in right side and store it in right
    find leftside as left^2;
    find rightside as right^2;

  3. if any two characters(except if any one of them is ‘?’) are not equal
    then ans is leftside*rightside

  4. if(leftside==1) ans is (rightside-1)

  5. if(rightside==1) ans is (leftside-1)
    6)else ans is (leftside)*(rightside-1)

3

My code for this problem :-

#include <bits/stdc++.h>
using namespace std;
int main()
{
  //write your code here
  
  int t; cin>>t;
  for(int i=0;i<t;i++)
  {
    string str; cin>>str;
    int flag=0; int size=str.length();
    int left=0,right=0;
    int z=0;
    for(int g=0;g<str.length()/2;g++)
    {
      //cout<<"indexes are "<<g<<" "<<(size/2+g)<<endl;
      //cout<<str[g]<<" "<<str[size/2+g]<<endl;
      
      if((str[g]!='?')&&(str[size/2+g]!='?')&&(str[g]!=str[size/2+g]))
        {flag=1; }
      if(str[g]=='?')
        left++;
      if(str[size/2+g]=='?')
        right++;
        z++;
    }
    
   // cout<<"left and right is "<<left<<" "<<right<<endl;
    
    int leftsum=1;
    while(left--)
    {
      leftsum=(leftsum*2)%1000000007;
    }
    int rightsum=1;
    while(right--)
    {
      rightsum=(rightsum*2)%1000000007;
    }
    //cout<<"leftsum and rightsum is "<<leftsum<<" "<<rightsum<<endl;
    //cout<<"flag is "<<flag<<endl;
    if(flag==1)
    {
      cout<<(leftsum*rightsum)%1000000007;
    }
    else if(leftsum==1)
    {
      cout<<rightsum-1;
    }
    else if(rightsum==1)
    {
      cout<<leftsum-1;
    }
    else 
    {
      cout<<((leftsum)*(rightsum-1))%1000000007;
    }
    cout<<endl;
  }
  
  return 0;
}