Submission

Score: 100

User: suphano

Problemset: จำนวนเฉพาะก่อนหน้า

Language: cpp

Time: 0.050 second

Submitted On: 2026-10-10 20:03:01

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main(){
    ll n;
    cin >> n;
    vector<bool> prime(n+1,true);
    for(int p = 2; p * p <= n; p++) {
        if (prime[p] == true) {
            for (ll i = p * p; i <= n; i += p) {  
                prime[i] = false;
            }
        }
    }
    vector<int> a;
    int count = 0;
    for(int i=2;i<n;i++){
        if(prime[i]){
            a.push_back(i);
            count++;
        }
    }
    a.push_back(n);
    
    //for(auto e : a){
      //  cout << e << " ";
    //}
    for(int i = 0 ;i<count+1;i++){
        if(a[i] == n){
            cout <<a[i-5]<< " " <<a[i-4]<<" "<<a[i-3]<<" "<<a[i-2]<<" "<<a[i-1];
        }
    }
    return 0;
}