Submission

Score: 100

User: chokun

Problemset: จำนวนเฉพาะก่อนหน้า

Language: cpp

Time: 0.002 second

Submitted On: 2026-10-14 16:15:33

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

bool isPrime(int n) {
    if (n <= 1) return false;
    if (n <= 3) return true;
    if (n % 2 == 0 || n % 3 == 0) return false;
    
    for (int i = 5; i * i <= n; i += 6) {
        if (n % i == 0 || n % (i + 2) == 0) return false;
    }
    return true;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    double input_N;
    if (!(cin >> input_N)) return 0;

    int n = (int)input_N;

    vector<int> primes;
    for (int i = n - 1; i >= 2; --i) {
        if (isPrime(i)) {
            primes.push_back(i);
        }
        if (primes.size() == 5) {
            break;
        }
    }

    reverse(primes.begin(), primes.end());

    for (int i = 0; i < 5; ++i) {
        cout << primes[i] << (i == 4 ? "" : " ");
    }
    cout << "\n";
}