Two Pointers

Find two numbers in a sorted array that add up to target

Check if string is palindrome (ignoring non-alphanumeric)

Reverse array of characters in-place using two pointers

Reverse only vowels in a string while keeping other characters in place

Reverse word order and remove extra spaces

Remove duplicates from sorted array in-place, return new length

Move all zeroes to end while maintaining order of non-zero elements

Return squares of sorted array in sorted order (handles negatives)

Find two lines that form container holding most water

Find all unique triplets that sum to zero

Sort array of 0s, 1s, 2s in-place using three pointers

Remove all instances of value in-place, return new length

Check if s is a subsequence of t

Merge two sorted arrays into first array in-place

Partition string so each letter appears in at most one part

Calculate how much rain water can be trapped between bars

Find three integers whose sum is closest to target

Check if string can be a palindrome by removing at most one character

Minimum boats to carry people with weight limit

Rotate array to the right by k steps using triple reverse

Find all unique quadruplets that sum to target

Check if typed string could be result of long pressing name

Find intersection of two arrays including duplicates

Remove duplicates allowing at most two of each element

Compare two strings with backspace characters (#)

Compress string in-place using read/write pointers