Round 1

1. Maximum sum rectangle in a 2D matrix.
2. https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/ , asked in a different manner but same question.

Round 2

1. Subsets that equal to a given sum in a tree. Numbers should be in the same path of traversal.
2. Zig-zag traversal in binary tree.