Skipped the naive two-loop approach and went straight to in-place.
Clarify whether the rotation is clockwise or counterclockwise and whether it should be done in-place. For an N×N matrix, the optimal in-place solution is to transpose the matrix and then reverse each row (for clockwise) or reverse each column (for counterclockwise). If the matrix is not square, discuss how to handle it, such as creating a new matrix of appropriate dimensions.
Pro tip: Mention that the in-place approach uses O(1) extra space and O(N^2) time, which is optimal. Also, note that for non-square matrices, the rotation changes dimensions, so in-place is not possible without additional space.
Ask about rotation direction (clockwise/counterclockwise), matrix dimensions (square or rectangular), and whether in-place rotation is required.
For square matrices, use the in-place transpose-and-reverse method. For rectangular matrices, create a new matrix of swapped dimensions and fill it accordingly.
Write clean code with clear variable names. For in-place, first transpose the matrix by swapping elements across the diagonal, then reverse each row (clockwise) or each column (counterclockwise).
State time complexity O(N^2) and space complexity O(1) for in-place, or O(N*M) space for rectangular matrices.
Walk through a small example (e.g., 2x2 or 3x3) to verify correctness, and consider edge cases like 1x1 matrix or empty matrix.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.