SMMR-T026: Duck Primes

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

typedef long long lli;

const int N = 1e6;
const int sqrtN = 1e3;

int main(){

    vector<bool> isPrime(N + 10, true);
    isPrime[1] = false;
    for(int i = 2; i <= sqrtN; ++i){
        if(isPrime[i]){
            for(int j = i + i; j <= N; j += i){
                isPrime[j] = false;
            }
        }
    }

    int Q;
    scanf("%d", &Q);
    for(int q = 1; q <= Q; ++q){
        lli x;
        scanf("%lld", &x);
        double rootX = sqrt(x);
        int fRootX = (int)rootX;
        if(rootX == fRootX && isPrime[fRootX]){
            cout << "YES\n";
        } else {
            cout << "NO\n";
        }
    }

    return 0;
}