Two Pointers Problem
K-diff Pairs in an Array (Easy Amazon)Two Sum - Unique pairs3Sum4Sum4Sum IITwo Sum - Less than or equal to targetSort ColorsSort Colors IIWindow SumValid Triangle NumberPartition Array IIMax Consecutive Ones IIReverse Vowels of a String (easy)Trapping Rain Water1498. Number of Subsequences That Satisfy the Given Sum ConditionSubstring With At Least K Distinct CharactersMinimum Window SubstringTwo Sum VIIthe kth subarray