0x07-rotate_2d_matrix

0x07. Rotate 2D Matrix

Algorithm Python

Description

This module provides a function rotate_2d_matrix(matrix) to rotate an n x n 2D matrix degree clockwise in-place.

Logic Explanation

The rotation of a matrix by 90 degree clockwise involves two steps:

1. Transpose the Matrix: Swap the elements across the main diagonal(top-left to bottom-right diagonal)
2. Reverse Each Row: After transposing, reverse each row of the matrix.

Algorithm

1. Transpose the Matrix

   • Iterate through the matrix rows and colunms.
   • Swap the element at (i, j) with the element at (j, i) for each pair (i, j) where i < j.

2. Reverse Each Row

   • Iterate through each row of the matrix.
   • Reverse the elements of each row.

Example

Consider the following matrix.

[[1, 2, 3],
[4, 5, 6],
[7, 8, 9]]

After rotating it 90 degree clockwise:

[[7, 4, 1],
[8, 5, 2],
[9, 6, 3]]

Usage

import matrix_rotation

matrix = [[1, 2, 3],
          [4, 5, 6],
          [7, 8, 9]]

matrix_rotation.ratate_2d_matrix(matrix)

for row in matrix:
    print(row)

Output

[7, 4, 1]
[8, 5, 2]
[9, 6, 3]