- Use an array
[prev, cur]to contain both new and old values.
- Be careful with boundaries, like we should use
row - 1 - iinstead of
row - i.
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.
Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]