Codeforces Round #828 (Div. 3) C. Traffic Light

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

int main()
{
    int T;cin>>T;
    while (T--)
    {
        int n;char c;cin>>n>>c;
        string s;cin>>s;
        s+=s;
        vector<int> a;
        for(int i=0;i<s.size();i++)
            if(s[i]=='g')
                a.push_back(i);
        int mx=0;
        for(int i=0;i<n;i++)
            if(s[i]==c)
            {
                int pos=lower_bound(a.begin(),a.end(),i)-a.begin();
                mx=max(mx,a[pos]-i);
            }
        cout<<mx<<endl;
    }
    return 0;
}