UVa 129 (回溯法) Krypton Factor

 1 #include <cstdio>
 2 
 3 char S[100];
 4 int n, L, cnt;
 5 
 6 int dfs(int cur)
 7 {
 8     if(cnt++ == n)
 9     {
10         for(int i = 0; i < cur; ++i)
11         {
12             if(i % 64 == 0 && i) puts("");
13             else if(i % 4 == 0 && i) printf(" ");
14             printf("%c", ‘A‘ + S[i]);
15         }
16         printf("\n%d\n", cur);
17         return 0;
18     }
19     for(int i = 0; i < L; ++i)
20     {
21         S[cur] = i;
22         int ok = 1;
23         for(int j = 1; j*2 <= cur + 1; ++j)
24         {
25             int equal = 1;
26             for(int k = 0; k < j; ++k)
27                 if(S[cur-k] != S[cur-k-j]) { equal = 0; break; }
28             if(equal) { ok = 0; break; }
29         }
30         if(ok) if(!dfs(cur+1)) return 0;
31     }
32     return 1;
33 }
34 
35 int main()
36 {
37     while(scanf("%d%d", &n, &L) == 2 && n)
38     {
39         cnt = 0;
40         dfs(0);
41     }
42 
43     return 0;
44 }