Rotate Image

描述

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]
]

题解

package algrithms

func rotate(matrix [][]int) {
	for i, temp, n := 0, 0, len(matrix)-1; i <= n/2; i++ {
		for j := i; j < n-i; j++ {
			temp = matrix[j][n-i]
			matrix[j][n-i] = matrix[i][j]
			matrix[i][j] = matrix[n-j][i]
			matrix[n-j][i] = matrix[n-i][n-j]
			matrix[n-i][n-j] = temp
		}
	}
}