【Leetcode】Rotate Image

タイトルリンク:https://leetcode.com/problems/rotate-image/
タイトル:
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?
考え方:
まずマトリクスを回転させ、各カラムを中軸対称に交換します.
アルゴリズム:

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