Cuckoo Hashing uses two hash tables with two hash functions.
Each key has exactly two possible locations: T1[h₁(key)] and T2[h₂(key)].
Insert: Place key in T1. If occupied, evict the resident to its alternate table.
This "cuckoo" displacement chains until an empty slot is found or a cycle is detected (triggering a rehash).
Lookup: Check both locations -- always O(1), just 2 probes.
Delete: Check both locations, remove if found -- O(1).