Leetcode#52 N-Queens II

原题地址

 

跟N-Queens几乎没差别，好像还更简单了呢

 

代码：

 1 int solve(int row, vector<bool> &col, vector<bool> left, vector<bool> right) {
 2   if (row == 0)
 3     return 1;
 4 
 5   vector<bool> avail(col.size(), false);
 6   for (int i = 0; i < col.size(); i++)
 7     avail[i] = !(col[i] || left[i] || right[i]);
 8 
 9   for (int i = 0; i < col.size() - 1; i++)
10     left[i] = left[i + 1];
11   left[col.size() - 1] = false;
12   for (int i = col.size() - 1; i > 0; i--)
13     right[i] = right[i - 1];
14   right[0] = false;
15 
16   int res = 0;
17   for (int i = 0; i < col.size(); i++) {
18     if (!avail[i])
19       continue;
20     col[i] = true;
21     if (i > 0) left[i - 1] = true;
22     if (i < col.size() - 1) right[i + 1] = true;
23     res += solve(row - 1, col, left, right);
24     if (i < col.size() - 1) right[i + 1] = false;
25     if (i > 0) left[i - 1] = false;
26     col[i] = false;
27   }
28 
29   return res;
30 }
31 
32 int totalNQueens(int n) {
33   vector<bool> col = vector<bool>(n, false);
34   vector<bool> left = vector<bool>(n, false);
35   vector<bool> right = vector<bool>(n, false);
36   return solve(n, col, left, right);
37 }

 

posted @ 2015-01-24 02:10  李舜阳  阅读(163)  评论(0)  编辑  收藏  举报