Description
You are given an n x n 2D matrix representing an image, rotate the image by 180 degrees (clockwise). You have to rotate the image in-place.
Examples
Input:
matrix = [[1,2,3],[4,5,6],[7,8,9]]Output:
[[9,8,7],[6,5,4],[3,2,1]]Explanation:
180 degree rotation.
Input:
matrix = [[1]]Output:
[1]Explanation:
Minimal case with a single-element matrix.
Input:
matrix = [[5,10],[15,20]]Output:
[[20,15],[10,5]]Explanation:
For a 2x2 matrix, rotating 180 degrees swaps the top-left with bottom-right, and top-right with bottom-left. Element at position (0,0) moves to (1,1), element at (0,1) moves to (1,0), element at (1,0) moves to (0,1), and element at (1,1) moves to (0,0).
Constraints
- •
n == matrix.length == matrix[i].length - •
1 ≤ n ≤ 20