Submission

xxxxxxxxxxxxxxxxxxxx

Score: 0

User: Ecir

Problemset: จำนวนเฉพาะก่อนหน้า

Language: cpp

Time: 0.035 second

Submitted On: 2025-01-14 17:40:52

#include <bits/stdc++.h>
using namespace std;
vector<int> prime;
bool p[7891218];
int main(){
	ios::sync_with_stdio(0);cin.tie(0);
	for(int i=2;i*i<=7891217;i++){
		if(p[i]==0){
//			cout << i << "\n";
			for(int j=2*i;j<=7891217;j+=i) p[j]=1;
		}
	}
  	prime.push_back(2);
  	for(int i=3;i<=7891217;i+=2) {
      if(p[i]==0) prime.push_back(i);
    }
//	for(auto e:prime) cout << e << " ";
	int n;cin >> n;
	int pos=lower_bound(prime.begin(),prime.end(),n)-prime.begin();
//	cout << pos ;
	if(pos<5) {
		for(int i=0;i<pos;i++){
			cout << prime[i] << " ";
		}
	}
	else {
		for(int i=pos-5;i<pos;i++){
			cout << prime[i] << " ";
		}
	}
	return 0;
}