Query on string by Bilas

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb push_back
#define pii pair<ll,ll>
#define ff first
#define ss second
#define mxx 100005
#define endl "\n"
const ll mod=1e9+7;

int main()
{
    ios::sync_with_stdio(0);
    //cin.tie(0);

    ll n,q;
    cin>>n>>q;
    string s;
    cin>>s;

    int arr[n+5],cnt=0;
    arr[0]=0;
    for(int i=1; i<s.size(); i++)
    {
        if(s[i]=='C' && s[i-1]=='A')
        {
            cnt++;
            arr[i]=cnt;
        }
        else
            arr[i]=cnt;
    }

    while(q--)
    {
        ll l,r;
        cin>>l>>r;
        l--,r--;

        cout<<arr[r]-arr[l]<<endl;
    }

    return 0;
}

https://www.hackerrank.com/contests/competencia-de-gente-perezosa-round-0-match-1-group-b/challenges/blacknerd-the-most-wanted-terrorist/problem