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Introduction to Hashing
On This Page
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 rehased, causing a temporary slowdown. |
Let's start solving the coding problems on Hashtables.
designgurus.cedar998
· 5 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.
On This Page
Implementing Hashtables in Different Languages
Code Examples
Limitations of Hashtables