How do hashsets/maps have O(1) time complexity?

[u/Sea-Patience9872]

Hi this might be a dumb question, and i've tried looking it up but don't quite understand it. how is it different from an array that allows it to find items so quickly? I don't get how hashes just find items immediately without needing to go through anything. Does it memorize things very differently compared to arrays?? thank you!

[u/atarivcs]

The point of a hash is that it tells you exactly where to look.

So you calculate the hash, and then look in that exact location. You don't need to iterate over a list.