HDU 1104Remainder

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<queue>
 4 #include<cstring>
 5 using namespace std;
 6 #define MAXN 1000010
 7 int c[MAXN];
 8 int fa[MAXN];
 9 int vis[MAXN];
10 int s[MAXN];
11 char op[5] = "+-*%";
12 
13 int mod(int a, int b) {
14     return ( a % b + b) % b;
15 }
16 
17 int main() {
18     int des, n, k, m, next, now, mo, cnt;
19     while (scanf("%d%d%d", &n, &k, &m) != EOF && k) {
20         mo = m*k;
21         queue <int> q;
22         des = mod(n + 1, k);
23         n = mod(n, mo);
24         memset(vis, 0, sizeof (vis));
25         q.push(n);
26         vis[n] = 1;
27         fa[n] = -1;
28         c[n] = -1;
29         while (!q.empty()) {
30             now = q.front();
31             q.pop();
32             for (int i = 0; i < 4; ++i) {
33                 if (i == 0)next = (now + m) % mo;
34                 else if (i == 1)next = mod(now - m, mo);
35                 else if (i == 2)next = now * m % mo;
36                 else next = now % m;
37                 if (!vis[next]) {
38                     vis[next] = 1;
39                     fa[next] = now;
40                     c[next] = i;
41                     if (next % k == des)
42                         goto L;
43                     q.push(next);
44                 }
45             }
46         }
47         printf("0\n");
48         continue;
49 L:
50         cnt = 0;
51         while (fa[next] >= 0) {
52             s[cnt++] = c[next];
53             next = fa[next];
54         }
55         printf("%d\n", cnt);
56         while (cnt)
57             printf("%c", op[s[--cnt]]);
58         printf("\n");
59 
60     }
61     return 0;
62 }