You are given an n x n 2D matrix matrix representing an image. Rotate the image by 90 degrees (clockwise).
You must rotate the image in-place, which means you have to modify the input 2D matrix directly. Do not allocate another 2D matrix for the rotation.
Input: matrix = [ [1,2,3], [4,5,6], [7,8,9] ] Output: [ [7,4,1], [8,5,2], [9,6,3] ]
Input: matrix = [ [5,1,9,11], [2,4,8,10], [13,3,6,7], [15,14,12,16] ] Output: [ [15,13,2,5], [14,3,4,1], [12,6,8,9], [16,7,10,11] ]
n == matrix.length == matrix[i].length1 <= n <= 20-1000 <= matrix[i][j] <= 1000