Rotate Image

Problem Statement

Given an n x n 2D matrix representing an image, rotate the image by 90 degrees clockwise.

• The rotation must be performed in-place; modify the input matrix directly.
• Do not allocate another 2D matrix for the rotation.

Example 1

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

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

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]]

Constraints

• n == matrix.length == matrix[i].length
• 1 <= n <= 20
• -1000 <= matrix[i][j] <= 1000

Code Template

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        # Your code here
        pass

Solutions

• Solution 1: This approach first transposes the matrix and then reverses each row to achieve the 90-degree clockwise rotation. The time complexity is O(n^2) and space complexity is O(1).

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