N皇后问题 

 1 #include <iostream>
 2 using namespace std;
 3 
 4 int map[12][12];
 5 int a[12] = {0, 1, 0, 0, 2, 10, 4, 40, 92, 352, 724, 2680};
 6 int n;
 7 
 8 bool check(int ii, int jj)
 9 {
10     for(int i = 0; i < n; ++i)
11         if(map[i][jj] || map[ii][i])
12             return false;
13     int k = ii + jj;
14     if(k <= n - 1)
15     {
16         for(int i = 0; i <= k; ++i)
17             if(map[i][k-i])
18                 return false;
19     }
20     else
21     {
22         for(int i = k-n+1; i <= n-1; ++i)
23             if(map[i][k-i])
24                 return false;
25     }
26     if(ii >= jj)
27     {
28         for(int i = ii - jj, j = 0; i < n; ++i, ++j)
29             if(map[i][j])
30                 return false;
31     }
32     else
33     {
34         for(int i = jj - ii, j = 0; i < n; ++i, ++j)
35             if(map[j][i])
36                 return false;
37     }
38     return true;
39 }
40 void dfs(int k, int n)
41 {
42     if(k == n)
43     {
44         a[n]++;
45     }
46     for(int i = 0; i < n; ++i)
47     {
48         if(map[k][i] == 0 && check(k, i))
49         {
50             map[k][i] = 1;
51             dfs(k + 1, n);
52             map[k][i] = 0;
53         }
54     }
55 }
56 int  main()
57 {
58     /*
59     for(int i = 1; i < 12; ++i)
60     {
61         memset(map, 0, sizeof(map));
62         n = i;
63         a[i] = 0;
64         dfs(0, i);
65         cout << ", " << a[i];
66     }
67     */
68     int k;
69     while(cin >> k && k)
70         cout << a[k] << endl;
71     //getchar();
72     return 0;
73 }
还是too young啊，写了好久。。。
posted @ 2011-07-11 21:13  georgechen_ena  阅读(99)  评论(0)    收藏  举报