Codeforces Round #215 (Div. 2) C. Sereja and Algorithm

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>

using namespace std;

int main(){
    string s ;
    cin >>s;
    int m;
    cin >>m;
    vector<int> l(m),r(m);
    for(int i = 0 ; i < m ; ++ i )
        cin >> l[i]>>r[i];

    int n = s.length();
    vector<int> x(n+1,0),y(n+1,0),z(n+1,0);
    for(int i = 0; i < n; ++ i){
        x[i+1] =x[i];
        y[i+1] = y[i];
        z[i+1] = z[i];
        if(s[i] == 'x')  x[i+1]++;
        else if(s[i] == 'y') y[i+1]++;
        else z[i+1]++;
    }

    for(int i = 0 ; i < m ; ++ i){
        if(r[i]-l[i]+1 < 3) cout<<"YES"<<endl;
        else{
            vector<int> num(3,0);
            num[0] = x[r[i]]-x[l[i]-1];
            num[1] = y[r[i]]-y[l[i]-1];
            num[2] = z[r[i]]-z[l[i]-1];
            sort(num.begin(),num.end());
            if((num[0] == num[1] && num[1] == num[2])||
               (num[2]-num[1] == 1 && num[1] == num[0]) ||
               (num[2]-num[1] == 0 && num[1] - num[0] == 1))
                cout<<"YES"<<endl;
            else cout<<"NO"<<endl;
        }
    }
    return 0;
}