Two pointers

sliding window

• left should point to first validate element in the window
  • while loop is to find next invalid element and evict it so left should not point to an invalid element in the first place
• 3. Longest Substring Without Repeating Characters
• 28. Implement strStr()
• 209. Minimum Size Subarray Sum
• 76. Minimum Window Substring
• 30. Substring with Concatenation of All Words
• 1423. Maximum Points You Can Obtain from Cards
• 340. Longest Substring with At Most K Distinct Characters
• 395. Longest Substring with At Least K Repeating Characters
• 1839. Longest Substring Of All Vowels in Order
• 1838. Frequency of the Most Frequent Element
• 1888. Minimum Number of Flips to Make the Binary String Alternating
• 438. Find All Anagrams in a String
• 1004. Max Consecutive Ones III

delete

• 27. Remove Element
• 26. Remove Duplicates from Sorted Array
• 283. Move Zeroes

tow sum

• 1. Two Sum
• 15. 3Sum
• 16. 3Sum Closest

interesting math proof

• 11. Container With Most Water

Misc

• 88. Merge Sorted Array
• 1775. Equal Sum Arrays With Minimum Number of Operations

left-right 2 points

• 42. Trapping Rain Water
• 680. Valid Palindrome II

2 points to 2 arrays

• 1868. Product of Two Run‐Length Encoded Arrays

intersection

• 986. Interval List Intersections