This Java code is an attempt to rotate a 2D...

This Java code is an attempt to rotate a 2D square matrix (NxN) 90 degrees clockwise. Specifically:

Detailed Explanation:

1. Input Validation:

   • The code first checks if the input matrix is null or has a length of 0. If so, the function returns immediately without performing any operations.

2. Extract Matrix Size:

   • m = matrix.length: The size (m x m) of the square matrix is extracted.

3. Create a New Result Matrix:

   • A new matrix, result, of the same size is created to store the rotated values.

4. Assign Rotated Values:

   • The two nested for-loops iterate over the input matrix, and for each (i, j) element in the original matrix:

     result[j][m - 1 - i] = matrix[i][j];
     

     This line maps the element from the original matrix[i][j] to its new position in the rotated matrix.

     The computation j determines the row in the new matrix, and m - 1 - i determines the column in the new matrix. This effectively rotates the elements 90 degrees clockwise.

5. Assign Result Back to Input (Ineffective):

   • matrix = result: At the end of the method, the rotated result matrix is assigned back to the matrix variable. However, this assignment does not modify the original input matrix because Java passes arrays (or objects) by reference, and the matrix parameter here is just a local reference. This means the original input matrix in the caller will remain unchanged.

Summary of What This Code Does:

• The functionality rotates a square matrix 90 degrees clockwise and stores the result in a new matrix (result).
• However, due to the way the matrix = result assignment works, the changes to the input matrix are not reflected for the caller after the method completes execution.