Search in a row wise and column wise sorted matrix

Search in a row wise and column wise sorted matrix (alt) is a DSA topic. In plain words you use it for names A→Z in the roll list. Don’t start with a slogan — start with that picture.

Smallest example: n log n vs n². Type it, run it, and say what you see. If you can do that from memory, you know Search in a row wise and column wise sorted matrix (alt).

From the example next to this theory: Search in a row wise and column wise sorted matrix (alt) — arrays give O(1) index access; matrices are arrays of arrays.

Trap — unstable sort when equal keys matter. Fix that before you talk about advanced DSA.

Viva — what is Search in a row wise and column wise sorted matrix (alt)? Then show n log n vs n². Then name the trap.