Problems.

Arrays & hashing

Two Sum3 ways Contains DuplicateBe the first Valid AnagramBe the first Product of Array Except SelfBe the first Top K Frequent ElementsBe the first

Two pointers

Valid PalindromeBe the first Container With Most WaterBe the first

Sliding window

Best Time to Buy and Sell StockBe the first Longest Substring Without Repeating CharactersBe the first

Stack

Valid Parentheses1 way

Binary search

Binary Search1 way

Intervals

Merge IntervalsBe the first

Graphs

Number of IslandsBe the first

Dynamic programming

Climbing StairsBe the first Maximum SubarrayBe the first

Easy Medium