leetcode-207-存在重复元素

class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        nums2 = set(nums)
        return not len(nums2)==len(nums)

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