Medium

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 3918 note: reverse n, take the range [min, max], and sum primes by trial division; test divisibility with %, never by comparing // with /

LeetCode note for Combination Sum IV, rebuilt from the original learning note

LeetCode note for Perfect Squares, rebuilt from the original learning note

LeetCode note for Network Delay Time, rebuilt from the original learning note

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

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

LeetCode note for Longest Increasing Subsequence, rebuilt from the original learning note

LeetCode note for Maximum Product Subarray, rebuilt from the original learning note

LeetCode 281 note: a queue of unfinished sources, take one value in turn and put the source back if anything remains; it generalizes to k sources

LeetCode 1059 note: trim outdegrees backward from the destination; a node is safe only when every outgoing edge leads to a safe node, and the destination itself must have no outgoing edges

LeetCode note for Decode Ways, rebuilt from the original learning note