方法一：

class Solution:
    # @param {integer[]} nums
    # @return {boolean}
    def containsDuplicate(self, nums):
        nums.sort()
        for x in range(len(nums)-1):
            if(nums[x]==nums[x+1]):
                return True
        return False
            
            

class Solution:
    # @param {integer[]} nums
    # @return {boolean}
    def containsDuplicate(self, nums):
        numSet=set()
        for num in nums:
            if num in numSet:
                return True
            numSet.add(num)        
        return False
        
            
 

方法三：（真是帥啊！）

class Solution:
    # @param {integer[]} nums
    # @return {boolean}
    def containsDuplicate(self, nums):
        return len(set(nums))!=len(nums)