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Introduction to Hashing
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Implementing Hashtables in Different Languages
Code Examples
Limitations of Hashtables
Implementing Hashtables in Different Languages
Different programming languages provide built-in implementations of Hashtables.
| Language | API (Hashtable Implementation) |
|---|---|
| Java | java.util.HashMap |
| Python | dict |
| C++ | std::unordered_map |
| JavaScript | Object or Map |
| C# | Dictionary<TKey, TValue> |
| Go | map |
Code Examples
Limitations of Hashtables
Although Hashtables are incredibly fast and efficient, they come with some drawbacks.
| Limitation | Explanation |
|---|---|
| High Memory Usage | Hashtables require extra memory to store keys, values, and handle collisions. |
| No Ordering | Unlike arrays or linked lists, Hashtables do not maintain insertion order. |
| Performance Degradation | If too many collisions occur, lookup time can degrade from O(1) to O(n). |
| Resizing Cost | When resizing occurs, all elements need to be rehashed, causing a temporary slowdown. |
Let's start solving the coding problems on Hashtables.
designgurus.cedar998
· 6 months ago
While I appreciate the theory of the three introductory lessons to the "Pattern: Hash Maps" section, I think they paint a misleading picture for someone focused on practical knowledge for the coding interview.
For example, I would have appreciated this page explaining (for JavaScript) when to use Set (no keys), Map (any key), and Object (string keys) for various common problems.
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On This Page
Implementing Hashtables in Different Languages
Code Examples
Limitations of Hashtables