Design

LeetCode 3885 note: a dict of current priorities plus a max-heap with lazy deletion, validated on pop

LeetCode 1570 note: store only non-zero (index, value) pairs, and compute the dot product by merging the two index-sorted lists with two pointers, multiplying only on equal indices

LeetCode 244 note: precompute each word’s positions (sorted by construction), then answer each query by merging the two position lists with two pointers, always advancing the smaller one

LeetCode 3829 note: one queue each for riders and drivers; cancellations only update a set, and canceled riders at the front are dropped before matching

LeetCode 3815 note: one max-heap per item, push a new entry on every bid change, and drop stale entries on query

LeetCode 3709 note: times are increasing, so store prefix sums and answer queries with two bisects; always parenthesize mid

Solving the Online Stock Span problem using monotonic stack approach

Implementing a stack with O(1) minimum retrieval using tuple-based approach

LeetCode 3508 note: a queue for FIFO, a set for duplicates, and an increasing time list per destination queried with bisect

LeetCode 208 note: each node is a children dict plus an is_end flag; insert, search and startsWith all walk down character by character

LeetCode 981 note: store a (timestamp, value) list per key, with timestamps increasing; get binary searches the last timestamp <= the query

LeetCode 705 note: a fixed number of buckets, with the key modulo the bucket count choosing the bucket and a list per bucket handling collisions