LeetCode【第217题】Contains Duplicate

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Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

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给定一个整数数组，找到该数组是否包含任何重复。 如果任何值在数组中至少出现两次，则函数应返回true，如果每个元素都不同，则函数应返回false。
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class Solution(object):
    def containsDuplicate(self, nums):
        """
        :type nums: List[int]
        :rtype: bool
        """
        if len(nums) == 0:
            return False
        else:
            arr = {}
            for i in range(len(nums)):
                if nums[i] in arr:
                    return True
                else:
                    arr[nums[i]] = i
            else:
                return False

class Solution(object):
    def containsDuplicate(self, nums):
        """
        :type nums: List[int]
        :rtype: bool
        """
        return len(nums) != len(set(nums))