关键在于 n%k n=n/k
#include<vector>
#include<cmath>
#include<iostream>
#include<cstdio>
using namespace std;

int main() {
	int n;
	vector<int> vec;
	while (cin >> n) {
		vec.clear();  //vec初始化
		while (n != 0) {
			vec.push_back(n % 2);
			n = n / 2;

		}
		for (int i = vec.size() - 1; i >= 0; i--) {
			cout << vec[i];
		}
		cout << endl;
	}

}