Rotate matrix

Here’s the clean summary — no code, just concepts:

🔁 Transpose

• Swap matrix[r][c] with matrix[c][r]

• Reflects matrix across the main diagonal

• Rows become columns

🔄 Row Reverse

• Reverse elements inside each row

• Flips matrix left ↔ right

• Horizontal flip

🔄 Column Reverse

• Reverse elements inside each column

• Flips matrix top ↔ bottom

• Vertical flip

🔄 Rotations (NxN Matrix)

✅ 90° Clockwise

• Transpose

• Then reverse each row

✅ 180°

• Reverse rows (top ↔ bottom)

• Then reverse each row

• Order does not matter

✅ 270° Clockwise (same as 90° CCW)

• Transpose

• Then reverse each column

🧠 Mental Shortcut

• Transpose = diagonal flip

• Row reverse = horizontal flip

• Column reverse = vertical flip

• Combine flips to get rotation

That’s the whole rotate-matrix game.