Zenefits

4 problems asked at Zenefits.

Easy (1)

Valid Parentheses (Leetcode 20)

Stack, Strings

Medium (1)

Min Stack (Leetcode 155)

Stack

Hard (2)

N-Queens (Leetcode 51 & 52)

Backtracking, Maths, Recursion...

Trapping Rain Water (LC 42)

Two Pointers, Prefix and Suffix Arrays, Stack