POJ - 1426 - Find The Multiple （DFS）

#include <map>
#include <set>
#include <cmath>
#include <deque>
#include <queue>
#include <stack>
#include <cstdio>
#include <cctype>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#define LL long long
#define ULL unsigned long long
#define INF 0x7fffffff
using namespace std;

int dfs(ULL pre, ULL x, ULL n) {
	if(pre > x) return 0;//判断是否溢出，溢出了就不是正解 
	if(x % n == 0) {
		cout << x << endl;
		return 1;
	}
	if(dfs(x, x * 10, n)) return 1;
	return dfs(x, x * 10 + 1, n);
}

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