Matrix problems often seem tricky because multiple rows and columns move at the same time. In this problem, we need to rotate an n × n matrix by 90 degrees clockwise without using any extra matrix. The key insight is that we don't need to perform the rotation directly. Instead, we can break it down into two simple operations that are easy to perform in-place. Problem Statement Given an n x n matrix representing an image, rotate the image by 90 degrees clockwise . Example Input: 1 2 3 4 5 6 7 8 9