Huawei

4 problems asked at Huawei.

Easy (2)

Two Sum (Leetcode 1)

Two Pointers, Arrays

Valid Parentheses (Leetcode 20)

Stack, Strings

Hard (2)

N-Queens (Leetcode 51 & 52)

Backtracking, Maths, Recursion...

Trapping Rain Water (LC 42)

Two Pointers, Prefix and Suffix Arrays, Stack