二分法解题

#include<bits/stdc++.h>
using namespace std;
int main(){
string a;
cin>>a;
int l=a.length();
int left=0,right=l-1,flag=0;
while(left<=right){
if(a[left]!=a[right]) flag=1;
left++;
right--;
}
if(flag==0) cout<<"Yes";
else cout<<"No";
return 0;
}