Understanding Hash Tables: Storage Mechanism, Collisions, and Resolution Techniques
This article explains how hash tables store key‑value pairs as array entries, describes hash collisions when different keys map to the same index, and outlines two common resolution methods—open addressing and chaining—while also providing visual illustrations and practical insights.
Hash tables fundamentally operate as arrays that store key‑value pairs (entries). The key is processed by a hash function to produce an index, determining where the entry is placed in the array.
When two different keys generate the same hash value, a hash collision occurs; the second key cannot occupy the already‑filled slot.
Collision Resolution Methods
The two main techniques for handling collisions are open addressing and chaining.
Open addressing searches sequentially for the next empty slot when the desired index is occupied, continuing until a free position is found.
Chaining links colliding entries together using a linked list; each array slot holds a pointer to the first entry, and subsequent colliding entries are added to the list via a next pointer.
Both methods aim to locate an alternative location for values that cannot be stored in their original hashed position.
The article also invites readers to discuss the topic, join a community of architects, and provides additional resources such as interview question collections and related technical articles.
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