def containsDuplicate(nums):
    """
    :type nums: List[int]
    :rtype: bool
    """
    # Single pointer, time limit exceeded FIXED
    dupes = set()
    for x in nums:
        if x in dupes:
            return True
        dupes.add(x)
    return False

print(containsDuplicate([1,2,3,1]))
print(containsDuplicate([1,2,3,4]))
print(containsDuplicate([1,1,1,3,3,4,3,2,4,2]))
print(containsDuplicate([1000000000,1000000000,11]))
print(containsDuplicate([1,5,-2,-4,0]))