搜索小练#5

题目

#include <cstdio>
#include <iostream>
#define ull unsigned long long int 
using namespace std;

int n, k;

inline void dfs (ull ans, int n, int weishu) {
	if (k == 0) return;
	if (weishu == 20) return;
	if (ans%n == 0) {
		cout << ans << '\n';
		k = 0;
		return;
	}
	dfs (ans*10, n, weishu+1);
	dfs (ans*10+1, n, weishu+1);
}

int main () {
	while (scanf ("%d", &n)&& n != 0) {
		k = 1;
		dfs (1, n, 1);
	}
	return 0;
}

this is a easy topic

but I can not make it unless I can read the answer

To tell the truth, I was very terrible

Although the topic is easy but I don't know how to solve it

I will also try my best to welcome the NOIP2020.

PS:

1.we need the 'weishu == 20'

because the ull can held '19' so we much let the ull can search all