POJ 1426 Find The Multiple

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 int n,limit = 20;
18 unsigned LL ans;
19 bool dfs(unsigned LL cur,int step) {
20     if(step == limit) return false;
21     if(cur%n == 0) {
22         ans = cur;
23         return true;
24     }
25     if(dfs(cur*10,step+1)) return true;
26     if(dfs(cur*10+1,step+1)) return true;
27     return false;
28 }
29 int main() {
30     while(scanf("%d",&n),n) {
31         if(dfs(1,0)) printf("%I64u\n",ans);
32     }
33     return 0;
34 }

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 int n,head,tail;
18 unsigned LL q[1000000];
19 unsigned LL bfs() {
20     head = tail = 0;
21     q[tail++] = 1;
22     while(head < tail) {
23         unsigned LL now = q[head++];
24         if(now%n == 0) return now;
25         unsigned LL tmp = now*10;
26         if(tmp%n == 0) return tmp;
27         q[tail++] = tmp;
28         tmp = now*10+1;
29         if(tmp%n == 0) return tmp;
30         q[tail++] = tmp;
31     }
32 }
33 int main() {
34     while(scanf("%d",&n),n) printf("%I64u\n",bfs());
35     return 0;
36 }