MLE on #11、#12求助

或者有谁给个特殊性质A做法也行

#include<bits/stdc++.h>
using namespace std;
int n;
long long ans;
string s,hsh;
unordered_map<string,int>mp;
int main(){
    cin>>n>>s;
    mp[""]=1;
    for(int i=0;i<n;i++){
        if(s[i]==hsh[hsh.size()-1]) hsh.pop_back();
        else hsh+=s[i];
        mp[hsh]++;
        ans+=mp[hsh]-1;
    }
    cout<<ans;
}