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POJ 1321 棋盘问题

http://poj.org/problem?id=1321

因为每一行每一列不能有棋子重复也就是没摆放一个棋子就终结了这一行和这一列的可能性

和8皇后一样

直接从第一行枚举 --> 深搜回溯即可

 1 #include <iostream>
 2 #include <stdio.h>
 3 #include <string.h>
 4 #define READ() freopen("in.txt", "r", stdin);
 5 using namespace std;
 6 
 7 int n, k, ans, tar = 0;
 8 char maze[16][16];
 9 bool row[16], culumn[16];
10 
11 void dfs(int x)
12 {
13     if (x == n) return;
14     int i = x;
15     for (int j = 0; j < n; j++)
16     {
17         if (maze[i][j] == '#' && culumn[j] == false && row[i] == false)
18         {
19             tar++;
20             if (tar == k)
21             {
22                 ans++;
23             }
24             else
25             {
26                 culumn[j] = true;
27                 row[i] = true;
28                 dfs(i+1);
29                 culumn[j] = false;
30                 row[i] = false;
31             }
32             tar--;
33         }
34     }
35     dfs(x+1);
36 }
37 
38 
39 int main()
40 {
41     while (~scanf("%d%d", &n, &k))
42     {
43         if (n == -1 && k == -1) break;
44         for (int i = 0; i < n; i++)
45         {
46             getchar();
47             for (int j = 0; j < n; j++)
48             {
49                 scanf("%c", &maze[i][j]);
50             }
51         }
52         memset(row, 0, sizeof(row));
53         memset(culumn, 0, sizeof(culumn));
54         tar = 0;
55         ans = 0;
56         dfs(0);
57         cout << ans << endl;
58     }
59     return 0;
60 }