[leetcode] rotate image

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

Rotate the image by 90 degrees (clockwise).

Note:
You have to rotate the image in-place, which means you have to modify the input 2D matrix directly.
DO NOT allocate another 2D matrix and do the rotation.

Example 1:
Given input matrix =
[
[1,2,3],
[4,5,6],
[7,8,9]
],
rotate the input matrix in-place such that it becomes:
[
[7,4,1],
[8,5,2],
[9,6,3]
]
Example 2:
Given input matrix =
[
[ 5, 1, 9,11],
[ 2, 4, 8,10],
[13, 3, 6, 7],
[15,14,12,16]
],
rotate the input matrix in-place such that it becomes:
[
[15,13, 2, 5],
[14, 3, 4, 1],
[12, 6, 8, 9],
[16, 7,10,11]
]

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  public void (int[][] matrix) { int length = matrix.length; for (int i = 0; i < length - 1; i++) { for (int j = 0; j < length - i; j++) { int temp = matrix[i][j]; matrix[i][j] = matrix[length - 1 - j][length - 1 - i]; matrix[length - 1 - j][length - 1 - i] = temp; } } for (int i = 0; i < length / 2; i++) { for (int j = 0; j < length; j++) { int temp = matrix[i][j]; matrix[i][j] = matrix[length - 1 - i][j]; matrix[length - 1 - i][j] = temp; } } }