More problems

This is a pretty standard one:

Given an n x n matrix containing only 1s and 0s, find the area of the largest rectangle (with sides parallel to the ends of the matrices) that contain only 1s.

Time Complexity required:

O(n^3) is trivial.

If anyone has an O(n^2) solution, please tell me!

The solution I have now is O(n^2 log n).