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For the “0. Rotate 2D Matrix” project, you are tasked with implementing an in-place algorithm to rotate an n x n 2D matrix by 90 degrees clockwise. This challenge requires a good understanding of matrix manipulation and in-place operations in Python. Below are the key concepts and resources that you need to grasp in order to successfully complete this project.

Concepts Needed:

  1. Matrix Representation in Python:

    • Understanding how 2D matrices are represented using lists of lists in Python.
    • Accessing and modifying elements in a 2D matrix.

  2. In-place Operations:

    • Performing operations on data without creating a copy of the data structure.
    • The importance of minimizing space complexity by modifying the matrix in place.

  3. Matrix Transposition:

    • Understanding the concept of transposing a matrix (swapping rows and columns).
    • Implementing matrix transposition as a step in the rotation process.

  4. Reversing Rows in a Matrix:

    • Manipulating rows of a matrix by reversing their order as part of the rotation process.

  5. Nested Loops:

    • Using nested loops to iterate through 2D data structures like matrices.
    • Modifying elements within nested loops to achieve the desired rotation.

Resources:

By understanding these concepts and utilizing the provided resources, you will be able to approach the problem methodically, first transposing the matrix and then reversing each row to achieve a 90-degree clockwise rotation. This project not only tests your ability to manipulate 2D matrices but also challenges you to think about optimizing your solution to operate in-place, thus improving their problem-solving and algorithmic thinking skills in Python.

Additional Resources

Requirements

General

  • Allowed editors: vi, vim, emacs
  • All your files will be interpreted/compiled on Ubuntu 20.04 LTS using python3 (version 3.8.10)
  • All your files should end with a new line
  • The first line of all your files should be exactly #!/usr/bin/python3
  • A README.md file, at the root of the folder of the project, is mandatory
  • Your code should use the pycodestyle style (version 2.8.0)
  • You are not allowed to import any module
  • All modules and functions must be documented
  • All your files must be executable

Tasks

0. Rotate 2D Matrix

Given an n x n 2D matrix, rotate it 90 degrees clockwise.

  • Prototype: def rotate_2d_matrix(matrix):
  • Do not return anything. The matrix must be edited in-place.
  • You can assume the matrix will have 2 dimensions and will not be empty.
jessevhedden$ cat main_0.py
#!/usr/bin/python3
"""
Test 0x07 - Rotate 2D Matrix
"""
rotate_2d_matrix = __import__('0-rotate_2d_matrix').rotate_2d_matrix

if __name__ == "__main__":
    matrix = [[1, 2, 3],
              [4, 5, 6],
              [7, 8, 9]]

    rotate_2d_matrix(matrix)
    print(matrix)

jessevhedden$
jessevhedden$ ./main_0.py
[[7, 4, 1],
[8, 5, 2],
[9, 6, 3]]
jessevhedden$

Repo:

  • GitHub repository: alx-interview
  • Directory: 0x07-rotate_2d_matrix
  • File: 0-rotate_2d_matrix.py