Paytm

4 problems asked at Paytm.

Easy (1)

Valid Parentheses (Leetcode 20)

Stack, Strings

Medium (2)

Min Stack (Leetcode 155)

Stack

Remove Duplicate Letters / Smallest Subsequence of Distinct Characters (Leetcode 316 / 1081)

Strings, Greedy, Hashing...

Hard (1)

Trapping Rain Water (LC 42)

Two Pointers, Prefix and Suffix Arrays, Stack