Rotating a matrix

Solving LeetCode 48. Rotate Image,

Here is a tutorial that can help you for a tricky little problem from LeetCode, and the solution in Swift. Have fun!

Prerequisites:

• Some programming experience

Difficulty: Easy | Normal | Challenging

The problem

We rotate the following matrix:

Which becomes the following:

Method 1: Simple rotation

Rotate the corners

The index of the corners can be derived from the size of the matrix. Here we describe the position as a coordinate, and then the derivation in Swift (where size = matrix.count).

top left = [0,0] = matrix[0][0]

top right = [0,3–1] = matrix[0][size — 1]

bottom right = [3–1, 3–1] = matrix[size-1][size-1]