Submission

Score: 100

User: letdown

Problemset: Twin, Cousin, and Sexy Prime

Language: cpp

Time: 0.310 second

Submitted On: 2025-10-12 12:39:19

#include <iostream>

using namespace std;
bool prime[70000002]; // reverse false=prime

int main() {
    int l, u;
    cin >> l >> u;
    // memset(prime, 1, sizeof(prime));

    for (int i = 2; i*i <= u + 6; i++) {
        if (!prime[i]) {
            for (int j = i*i; j <= u + 6; j += i) {
                prime[j] = true;
            }
        }
    }

    int tw=0, cz=0, sx=0;
    for (int i = l; i <= u; i++) {
        if (prime[i]) continue;

        if ((i >= 4 && !prime[i-2]) || !prime[i+2]) tw++;
        if ((i >= 6 && !prime[i-4]) || !prime[i+4]) cz++;
        if ((i >= 8 && !prime[i-6]) || !prime[i+6]) sx++;
    }

    cout << tw << "\n" << cz << "\n" << sx;
}