POJ-1426(Find The Multiple) dfs

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

typedef unsigned long long ull;
int visit;
void dfs(ull n, int m, int k)
{
if(visit) return;
if(n % m == 0)
{
printf("%I64u\n", n);
visit = 1;
return ;
}
if(k == 19) return;

dfs(n*10, m, k+1);
dfs(n*10 + 1, m, k + 1);
}
int main()
{
int t;
while(scanf("%d", &t) != EOF && t)
{
visit = 0;
dfs(1, t, 0);
}
return 0;
}