Question

I have an array of structures, ~100 unique elements, and the structure is not large. Due to legacy code, to find an element in this array i use a hash function to find a likely starting point to start looping from until i find the element i want.

My question is this: Is the hash function (and resulting hash table) overkill ?

I know for large tables hashing is essential for good response time, but for a table this size ?

More succinctly, is there a table size below which writing a hash function is unnecessary ?

Language agnostic answers please.

Thanks,

Answer 1

A hash lookup trades better scalability for a bigger up-front computation cost. There is no inherent table size, as it depends on the cost of your hash function. Roughly speaking, if calculating your hash function has the same cost as one hundred equality comparisons, then you could only theoretically benefit from the hash map at some point above one hundred items. The only way to get specific answers for your case is to measure the performance.

My guess though, is that a hash map for 100 items for performance reasons is overkill.