【leetcode刷题笔记】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?

题解：

如果要原地算法的话，就只能用交换实现了。首先把matrix[i][j]和matrix[j][i]交换，然后把整个矩阵左右翻转，如下图所示：

1 2 3 1 4 7 7 4 1

4 5 6 2 5 8 8 5 2

7 8 9 3 6 9 9 6 3

JAVA代码：

 public class Solution {

     public void rotate(int[][] matrix) {

         int n = matrix.length;

         for(int i = 0;i < n;i++){

             for(int j = i+1;j < n;j++){

                 int temp = matrix[i][j];

                 matrix[i][j] = matrix[j][i];

                 matrix[j][i] = temp;

             }

             for(int j = 0;j < n/2;j++){

                 int temp = matrix[i][j];

                 matrix[i][j] = matrix[i][n-j-1];

                 matrix[i][n-j-1] = temp;

             }

         }

     }

 }

巴特西

【leetcode刷题笔记】Rotate Image

最新文章

热门文章