Time complexity of set in Java

Question

Can someone tell me the time complexity of the below code?

a is an array of int.

Set set = new HashSet();
for          


        

Answer 1

i believe its O(n) because you loop over the array, and contains and add should be constant time because its a hash based set. If it were not hash based and required iteration over the entire set to do lookups, the upper bound would be n^2.

Integers are immutable, so the space complexity would be 2n, which I believe simplifies to just n, since constants don't matter.

If you had objects in the array and set, then you would have 2n references and n objects, so you are at 3n, which is still linear (times a constant) space constraints.

EDIT-- yep "This class offers constant time performance for the basic operations (add, remove, contains and size), assuming the hash function disperses the elements properly among the buckets."

see here.