NOTE
Hash Table / Hash Map
Hashing, buckets, collisions, load factor, resizing, and expected versus worst-case lookup complexity.
This is a historical learning note and may contain outdated or incomplete understanding.
A hash table maps a key’s hash to a bucket and resolves collisions through chaining/open addressing/another collision strategy.
With a good hash distribution and controlled load factor, lookup/insert/delete are expected O(1). Worst-case behavior can degrade when many keys collide or adversarial input defeats the strategy.
Resizing changes table capacity and redistributes entries. Correctness depends on equality/hash contracts, not only the hash function.