Home/ Questions/Q 726895
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-14T06:30:15+00:00

So here is my problem. I want to store 2-tuple (key, val) and want

  • 0

So here is my problem. I want to store 2-tuple (key, val) and want to perform following operations:

  • keys are strings and values are Integers
  • multiple keys can have same value
  • adding new tuples
  • updating any key with new value (any new value or updated value is greater than the previous one, like timestamps)
  • fetching all the keys with values less than or greater than given value
  • deleting tuples.

Hash seems to be the obvious choice for updating the key’s value but then lookups via values will be going to take longer (O(n)). The other option is balanced binary search tree with key and value switched. So now lookups via values will be fast (O(lg(n))) but updating a key will take (O(n)). So is there any data-structure which can be used to address these issues?

Thanks.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    I’d use 2 datastructures, a hash table from keys to values and a search tree ordered by values and then by keys. When inserting, insert the pair into both structures, when deleting by key, look up the value from the hash and then remove the pair from the tree. Updating is basically delete+insert. Insert, delete and update are O(log n). For fetching all the keys less than a value lookup the value in the search tree and iterate backwards. This is O(log n + k).

    The choices for good hash table and search tree implementations depend a lot on your particular distribution of data and operations. That said, a good general purpose implementation of both should be sufficient.

    • 0