### Question :

What is time complexity of a list to set conversion?

I’ve noticed the table of the time complexity of set operations on the python official website. But i just wanna ask what’s the time complexity of converting a list to a set, for instance,

```
l = [1, 2, 3, 4, 5]
s = set(l)
```

I kind of know that this is actually a hash table, but how exactly does it work? Is it O(n) then?

##
Answer #1:

Yes. Iterating over a list is `O(n)`

and adding each element to the hash set is `O(1)`

, so the total operation is `O(n)`

.