Greedy

LeetCode note for Wiggle Subsequence, rebuilt from the original learning note

LeetCode note for Best Time To Buy And Sell Stock II, rebuilt from the original learning note

LeetCode 3919 note: walk one step at a time, each costing 1 (when the next index is the closest) or the gap; jumping is never cheaper, so answer queries with prefix sums

LeetCode note for Jump Game, rebuilt from the original learning note

LeetCode note for Jump Game II, rebuilt from the original learning note

LeetCode 3914 note: adding x to a range raises only the difference at its left edge by x, so the answer is the sum of all drops

LeetCode 1537 note: two sorted arrays can switch only at shared values; merge with two pointers, keep a running sum per path, and at a shared value set both to the larger sum plus that value

LeetCode 976 note: after sorting, check consecutive triples from the largest down; the first with a + b > c gives the largest perimeter

LeetCode 581 note: scanning left to right with a running max, the last index below it is the right boundary; scanning right to left with a running min, the last index above it is the left boundary

LeetCode 3684 note: all values are positive, so deduplicate and take the k largest in descending order

LeetCode 3555 note: every length-k window is one instance of LeetCode 581; with n only 1000, two O(k) scans per window are enough

LeetCode 1793 note: expand from k toward the larger neighbor each step so the minimum stays as large as possible for each length; at a boundary, only the other side can grow