Which of these implementation strategies attempts to approximate random access into an array?
Answer
a. doubly linked nodes
b. sorting
c. hashing
d. singly linked nodes
e. recursion
The correct answer and explanation is:
The correct answer is c. hashing.
Explanation:
Random access to an array refers to the ability to access any element in the array in constant time, typically using an index (e.g., accessing array[i] in constant time O(1)). In contrast, some data structures require traversal to locate an element, making random access inefficient or impossible.
Out of the options provided, hashing attempts to approximate random access by mapping data to specific locations using a hash function. A hash function takes an input (or key) and computes an index in an array, making it possible to directly access the element associated with the key. If collisions occur (when two keys hash to the same index), methods like chaining or open addressing are used to resolve them. Despite potential collisions, hashing provides an average-case constant time complexity for lookups, making it the closest implementation strategy to random access.
Here’s how the other options compare:
- a. Doubly linked nodes: Doubly linked lists allow traversal in both directions, but they do not provide random access. To access a particular element, you must traverse the list sequentially, which means it takes linear time
O(n)in the worst case. - b. Sorting: Sorting refers to ordering elements in a specific sequence (e.g., ascending or descending). While sorting can optimize search operations (like binary search), it does not inherently provide random access to elements. Random access requires direct indexing, which sorting does not provide.
- d. Singly linked nodes: Singly linked lists allow traversal in one direction and do not support random access. Just like doubly linked lists, they require sequential traversal to access a specific element, resulting in a time complexity of
O(n). - e. Recursion: Recursion is a method of solving problems where a function calls itself. While recursion can be used to traverse or manipulate data structures, it does not provide random access to elements. It may be useful for tasks like searching or traversing a tree, but not for accessing elements directly like in an array.
Thus, hashing is the strategy that best approximates random access by allowing direct access to elements using computed indices.