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Rotate Image - Leetcode 48 - Python

 


Rotate Image



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.


class Solution:

    def rotate(self, m: List[List[int]]) -> None:

        

        """

        Do not return anything, modify matrix in-place instead.

        """

        

        l, r = 0, len(m)-1

        

        while l < r :

            for i in range(r-l): 

                t, b = l, r

                

                # tl in temp

                temp = m[t][l+i]

                

                # bl -> tl

                m[t][l+i] = m[b-i][l]

                

                # br -> bl

                m[b-i][l] = m[b][r-i]

                

                #  tr -> br

                m[b][r-i] = m[t+i][r]

                

                # temp -> tr

                m[t+i][r] = temp

                

            r -= 1

            l += 1



Explaintion :



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