Rotate Image

Medium~20 min

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees clockwise.

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.

Return the matrix after rotating it.

Examples

Example 1

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

Output: [[7,4,1],[8,5,2],[9,6,3]]

Explanation: The 3x3 matrix is rotated 90 degrees clockwise. The first column [1,4,7] becomes the first row [7,4,1] reversed.

Example 2

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]]

Explanation: The 4x4 matrix is rotated 90 degrees clockwise in-place.

Constraints

n == matrix.length == matrix[i].length
1 <= n <= 20
-1000 <= matrix[i][j] <= 1000
Expected time complexity: O(n²)

Code

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Output

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