Rotating 90 degrees clockwise is equivalent to:

1. Reversing the matrix rows (vertical flip).
2. Transposing the matrix (swapping matrix[i][j] with matrix[j][i]).

1. Reverse the order of rows: matrix.reverse().
2. Transpose the matrix:
   • Iterate for i from 0 to n-1.
   • Iterate for j from i+1 to n-1.
   • Swap matrix[i][j] and matrix[j][i].

• Time Complexity: O(N^2).
• Space Complexity: O(1).

def rotate(matrix):
    # 1. Reverse up to down
    matrix.reverse()
    
    # 2. Transpose
    n = len(matrix)
    for i in range(n):
        for j in range(i + 1, n):
            matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]