PayPal

5 problems asked at PayPal.

Easy (2)

Two Sum (Leetcode 1)

Two Pointers, Arrays

Valid Parentheses (Leetcode 20)

Stack, Strings

Medium (1)

Longest Substring Without Repeating Characters (leetcode 3)

Sliding Window, Strings, Hashing

Hard (1)

Trapping Rain Water (LC 42)

Two Pointers, Prefix and Suffix Arrays, Stack

Not Specified (1)

Best Time to Buy and Sell Stock

Arrays, DP