Understanding How Hash Tables Store Data and Resolve Collisions
This article explains the fundamentals of hash tables, how they store key‑value pairs, the nature of hash collisions, and the two primary resolution strategies—open addressing and chaining—illustrated with clear examples and diagrams.
How Hash Tables Store Data
A hash table is essentially an array that stores key‑value Entry objects.
For example, a student ID can serve as the key; the hash function computes an index that determines where the entry is placed in the array.
Hash Collisions
A hash collision occurs when two different keys (e.g., two students' IDs) produce the same hash value, causing both entries to map to the same array position.
Resolution Methods
Collisions can be resolved using open addressing or chaining.
Open addressing means that if the calculated slot is occupied, the algorithm probes subsequent slots (slot 2, slot 3, …) until an empty one is found.
Chaining stores a linked list at each array position. When a collision occurs, the new entry is added to the list via a next pointer that references another entry stored elsewhere.
If further collisions happen, additional entries are linked, forming a chain.
Summary:
Open addressing and chaining both find the next empty position to store colliding values.Signed-in readers can open the original source through BestHub's protected redirect.
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