48_Rotate_Image.py

"""
https://leetcode.com/problems/rotate-image/
"""
"""
You are given an n x n 2D matrix representing an image.
Rotate the image by 90 degrees (clockwise).

Note:
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.

Example 1:
    Given input matrix = 
    [
      [1,2,3],
      [4,5,6],
      [7,8,9]
    ],
    
    rotate the input matrix in-place such that it becomes:
    [
      [7,4,1],
      [8,5,2],
      [9,6,3]
    ]
Example 2:
    Given input matrix =
    [
      [ 5, 1, 9,11],
      [ 2, 4, 8,10],
      [13, 3, 6, 7],
      [15,14,12,16]
    ], 
    
    rotate the input matrix in-place such that it becomes:
    [
      [15,13, 2, 5],
      [14, 3, 4, 1],
      [12, 6, 8, 9],
      [16, 7,10,11]
    ]
"""
class Solution:
    def rotate(self, matrix):
        """
        Do not return anything, modify matrix in-place instead.
        """
        k = len(matrix)
        i, j = 0, 0
        while k>1:
            self.rotateCircle(matrix, k, i, j)
            k -= 2
            i, j = i+1, j+1


    def rotateCircle(self, matrix, k, i, j):
        for l in range(k-1):
            matrix[i][j+l], matrix[i+l][j+k-1], matrix[i+k-1][j+k-1-l], matrix[i+k-1-l][j] = \
                matrix[i+k-1-l][j], matrix[i][j+l], matrix[i+l][j+k-1], matrix[i+k-1][j+k-1-l]

matrix = [
      []
    ]
x = Solution()
x.rotate(matrix)
print(matrix)