Rotate Matrix by 90 Degrees (Clockwise)?

Short answer: void RotateMatrix(int[][] matrix) {

Example code

int n = matrix.Length; // Transpose for (int i = 0; i < n; i++)
for (int j = i; j < n; j++) (matrix[i][j], matrix[j][i]) = (matrix[j][i], matrix[i][j]); // Reverse each row for (int i = 0; i < n; i++)
{
int left = 0, right = n - 1; while (left < right) { (matrix[i][left], matrix[i][right]) = (matrix[i][right], matrix[i][left]); left++; right--; }
}
} Explanation: Transpose matrix and then reverse each row to rotate clockwise by 90°.

Real-world example (ShopNest)

In coding rounds, state complexity aloud, write a clear ShopNest-flavored example (orders, carts), then handle edge cases (empty list, null, overflow).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.