125.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?

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分析：手动分析出规律：matrix[i][j] = matrix[n-1-j][i]

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