Two Pointers
Scan from both ends or with two indices instead of nested loops.
- 23.125. Valid Palindrome
- 24.167. Two Sum II - Input Array Is Sorted
- 25.15. 3Sum
- 26.11. Container With Most Water
- 27.42. Trapping Rain Water
- 28.1768. Merge Strings Alternately
- 29.344. Reverse String
- 30.88. Merge Sorted Array
- 31.26. Remove Duplicates from Sorted Array
- 32.680. Valid Palindrome II
- 33.18. 4Sum
- 34.189. Rotate Array
- 35.881. Boats to Save People