Submission

Score: 100

User: Patn01Z

Problemset: จำนวนเฉพาะก่อนหน้า

Language: cpp

Time: 0.004 second

Submitted On: 2026-10-09 21:14:31

#include <iostream>
#include <cmath>
using namespace std;

bool prime(int N){
    if(N<2){
        return false;
    }
    else if(N==2){
        return true;
    }
    else if(N%2==0){
        return false;
    }
    else{
        for(int i=3;i<=sqrt(N);i+=2){
            if(N%i==0){
                return false;
            }
        }
    }
    return true;
}

int main(){
    bool even=false;
    int n=0;
    cin >> n;
    int N=n;
    if(n%2==0){
        even=true;
    }
    if(even){
        n=n-1;
    }
    else{
        n=n-2;
    }


    int a[5]={0};
    int count=0;

    for(int i=n;count<5;i-=2){
        if(prime(i)){
            a[4-count]=i;
            count++;
        }
    }

    for(int i=0;i<5;i++){
        cout << a[i] << " ";
    }
}