Two-Pointers

Sliding window with a set and running sum; two pointers to keep the subarray unique.

LeetCode 2441 note: keep positives and absolute values of negatives in separate sets and take the largest common value; absolute values alone mistake same-sign duplicates for pairs

LeetCode Problem Solving - Variable Size Sliding Window with Hash Map

LeetCode Problem Solving - Variable Size Sliding Window with Character Counting

LeetCode Problem Solving - Variable Size Sliding Window with Zero Counting

LeetCode 2410 note: sort both sides, then same-direction pointers match the weakest player with the smallest trainer that is good enough

Fixed-size windows, variable windows for longest / shortest, counting subarrays (at most K minus at most K - 1, count += left for at least K), and monotonic deques for window extremes

LeetCode 1768 note: take characters in turn with one index, then append whatever remains of the longer string

LeetCode 2000 note: find the first index i of ch, reverse word[:i + 1] and append the rest; return the word unchanged if ch is absent

LeetCode 3069 note: simulate the rule: the first two go to separate arrays, then each element joins the array whose last element is larger

LeetCode 611 note: sort, fix the longest side k, and use two pointers for the shorter sides; when the sum is large enough every i in between works, adding j - i at once

LeetCode 165 note: split on dots, compare revision by revision as integers, and treat missing revisions of the shorter version as 0