Trees vs Hash Tables

Comparison Between Trees and Hash Tables

Both of these data structures can be used for the same job, but their performance would vary based on the nature of your program. Let’s take a look at some of the factors we need to keep in mind when deciding the appropriate data structure.

Basic Operations

On average, hash tables can perform search, insertion, and deletion in constant time whereas trees usually work in O(log n). However, in the worst-case scenario, the performance of hash tables can come down to O(n) where n is the total number of hash entries. An AVL tree would maintain O(log n) even in the worst case.

Hash Function

An efficient hash table requires a smart hash function that​ would distribute the keys over all the space that is available to us. A tree is simpler to implement in this regard as it accesses extra space only when needed and no hash function is required to optimize its structure.

Order of Data

If our application needs data to be ordered in a specific sequence, trees would prove more useful because a BST or an AVL tree maintains order. Hash tables are the smarter choice if your data can be stored randomly.