2014-03-20 04:08

题目:八皇后问题。

解法:DFS解决。

代码:

 1 // 9.9 Eight-Queen Problem, need I say more?
 2 #include <cstdio>
 3 #include <vector>
 4 using namespace std;
 5 
 6 class Solution
 7 {
 8 public:
 9     void eigthQueens(int n, vector<vector<int> > &result) {
10         if (n < 1) {
11             return;
12         }
13         
14         vector<int> v;
15         dfs(0, n, v, result);
16         v.clear();
17     }
18 private:
19     void dfs(int idx, int n, vector<int> &v, vector<vector<int> > &result) {
20         if (idx == n) {
21             result.push_back(v);
22             return;
23         }
24 
25         int i, j;
26         for (i = 0; i < n; ++i) {
27             for (j = 0; j < idx; ++j) {
28                 if (v[j] == i || myabs(idx - j) == myabs(i - v[j])) {
29                     // conflict
30                     break;
31                 }
32             }
33             if (j == idx) {
34                 v.push_back(i);
35                 dfs(idx + 1, n, v, result);
36                 v.pop_back();
37             }
38         }
39     }
40     
41     int myabs(int n) {    
42         return (n >= 0 ? n : -n);
43     }
44 };
45 
46 int main()
47 {
48     vector<vector<int> > result;
49     Solution sol;
50     int n;
51     int i, j, k;
52     
53     while (scanf("%d", &n) == 1 && n > 0) {
54         sol.eigthQueens(n, result);
55         for (k = 0; k < (int)result.size(); ++k) {
56             for (i = 0; i < n; ++i) {
57                 for (j = 0; j < result[k][i]; ++j) {
58                     putchar('0');
59                 }
60                 putchar('1');
61                 for (j = result[k][i] + 1; j < n; ++j) {
62                     putchar('0');
63                 }
64                 putchar('\n');
65             }
66             putchar('\n');
67         }
68         printf("%d\n", (int)result.size());
69         for (i = 0; i < (int)result.size(); ++i) {
70             result[i].clear();
71         }
72         result.clear();
73     }
74     
75     return 0;
76 }

 

 posted on 2014-03-20 04:08  zhuli19901106  阅读(183)  评论(0编辑  收藏  举报