暴力题解

先算在输出

#include<bits/stdc++.h>
using namespace std;
int func(int n) {
    for (int i = 2; i < n; i++)
        if (n % i == 0) return false;
    return true;
}
int main() {
	bool a[20010] = {};
    for (int i = 1; i <= 20010; i++) {
        if (i == 2) a[i] = 1;
        else if (func(i)) a[i] = 1;
        else a[i] = 0;
    }
    a[1] = 0;
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++)
        if (a[i] == 1) cout << i << " ";
    return 0;
}