c++写题日记001

[好好]

 思路：用一个数组记录每个位点的状态，然后通过for循环改变，最后输出结果

#include <iostream>
using namespace std;
int n;
const int N = 5001;
int q[N] = { 0 };

int main()
{
	cin >> n;
	for (int i = 2; i <= n; i++)
	{
		for (int j = 1; j * i <= n; j++)
		{
			if (q[j * i] == 0)  q[j * i] = 1;
			else  q[j * i] = 0;
        }
  	}
	for (int i = 1; i <= n; i++)
	{
		if (q[i] == 0) cout << i << " ";
	}
        return 0;
}