POTD #1 Rotate by 90 degree - Matrix Anticlockwise | Geeks For Geeks

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After a long time, i tried competitive programming. Seems i need to do it more. This is a geeks for geeks POTD (Problem of the day) problem.

Link: https://www.geeksforgeeks.org/problems/rotate-by-90-degree-1587115621/1

Given a square matrix mat[][] of size n x n. The task is to rotate it by 90 degrees in an anti-clockwise direction without using any extra space. 

Input:

Input: mat[][] = [[1, 2, 3],
                [4, 5, 6]
                [7, 8, 9]]
Output: Rotated Matrix:
[3, 6, 9]
[2, 5, 8]
[1, 4, 7]

Input: mat[][] = [[1, 2],                [3, 4]]Output: Rotated Matrix:[2, 4][1, 3]

Solution

I tried to reverse the each row and found the transpose of the matrix. Since i am aware of transpose , i directly went to this approach.

#User function Template for python3class Solution:        #Function to rotate matrix anticlockwise by 90 degrees.    def rotateby90(self, mat):         # code here        n = len(mat)                    # reversing        for row in mat:            i = 0            j = len(row) - 1            while i  < j:                row[i], row[j] = row[j], row[i]                i += 1                j -= 1                                            # Performing Transpose        for i in range(n):            for j in range(i + 1, n):                mat[i][j], mat[j][i] = mat[j][i], mat[i][j]

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