Rotate Image

Basic Problem: Rotate 90° Clockwise

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees clockwise, in place. You have to modify the input 2D matrix directly. Do not allocate another 2D matrix to do this task.

Constraints:

• The matrix is guaranteed to be a square matrix (i.e., n x n).
• You must perform this in place, without using extra space for another matrix.

Examples:

1. Input: matrix = [ [1, 2, 3], [4, 5, 6], [7, 8, 9] ] Output: matrix = [ [7, 4, 1], [8, 5, 2], [9, 6, 3] ]

2. Input: matrix = [ [ 5, 1, 9,11], [ 2, 4, 8,10], [13, 3, 6, 7], [15,14,12,16] ] Output: matrix = [ [15,13, 2, 5], [14, 3, 4, 1], [12, 6, 8, 9], [16, 7,10,11] ]

Hints:

• Consider rotating the matrix layer by layer, starting from the outermost layer.
• You can transpose the matrix first and then reverse each row to achieve the rotation.

Solution:

Here's a sample solution in Python: python def rotate(matrix): n = len(matrix) for i in range(n): matrix[i] = matrix[i][::-1] # reverse each row for i in range(n): for j in range(i, n): matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j] # transpose

This solution first reverses each row of the matrix, and then transposes the matrix to achieve the 90-degree clockwise rotation.