leetcode每日一题：217. 存在重复元素

输入: [1,2,3,1]
输出: true

输入: [1,2,3,4]
输出: false

输入: [1,1,1,3,3,4,3,2,4,2]
输出: true

class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        if not nums or len(nums) < 1:
            return False
        # set 
        '''
        len1 = len(nums)
        set1 = set(nums)
        len2 = len(set1)
        if len2 < len1:
            return True
        return False
        '''
        # 哈希表
        '''
        res = {}
        for num in nums:
            if num in res:
                return True
            res[num] = 1
        return False
        '''
        # 排序
        nums_sort = sorted(nums)
        length = len(nums)
        for i in range(0, length-1):
            if nums_sort[i] == nums_sort[i+1]:
                return True
        return False