[LeetCode] Rotate Image

You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

Follow up:
Could you do this in-place?

需要O(N)的辅助空间，应该有个O(1)空间的。但似乎比较复杂。

 1 class Solution {
 2 public:
 3     void rotate(vector<vector<int> > &matrix) {
 4         // Start typing your C/C++ solution below
 5         // DO NOT write int main() function
 6         vector<int> temp(matrix.size());
 7         
 8         int begX = 0;
 9         int begY = 0;
10         int endX = matrix.size() - 1;
11         int endY = matrix[0].size() - 1;
12         
13         while(begX < endX)
14         {
15             for(int i = begY + 1; i <= endY - 1; i++)
16                 temp[i] = matrix[begX][i];
17                 
18             int index = endX - 1;
19             for(int i = begY + 1; i <= endY - 1; i++)
20                 matrix[begX][i] = matrix[index--][begY];
21                 
22             index = begY + 1;
23             for(int i = begX + 1; i <= endX - 1; i++)
24                 matrix[i][begY] = matrix[endX][index++];
25              
26             index = endX - 1;   
27             for(int i = begY + 1; i <= endY - 1; i++)
28                 matrix[endX][i] = matrix[index--][endY];
29                 
30             for(int i = begX + 1; i <= endX - 1; i++)
31                 matrix[i][endY] = temp[i];
32                 
33             int t = matrix[begX][begY];
34             
35             matrix[begX][begY] = matrix[endX][begY];
36             matrix[endX][begY] = matrix[endX][endY];
37             matrix[endX][endY] = matrix[begX][endY];
38             matrix[begX][endY] = t;
39             
40             begX++;
41             begY++;
42             endX--;
43             endY--;
44         }
45     }
46 };
posted @ 2012-11-18 18:16  chkkch  阅读(748)  评论(0)  编辑  收藏  举报