Problem URL: Contains duplicate

We are given a list of integers. We have to find out whether we have any duplicate or not. We can store the elements in a hashset while iterating through the list. We the item is already present in the hashset then we immediately return true as we already have duplicate. If we finish the iteration of the whole list, that means we don't have any duplicate, so we return false.

class Solution:
def containsDuplicate(self, nums: List[int]) -> bool:
    hashset = set()
    for i in range(len(nums)):
        if nums[i] in hashset:
            return True
        hashset.add(nums[i])
    return False

Time Complexity: O(n)
Space Complexity: O(n)