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217. Contains Duplicate

Difficulty Topics

Description

Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.

 

Example 1:

Input: nums = [1,2,3,1]
Output: true

Example 2:

Input: nums = [1,2,3,4]
Output: false

Example 3:

Input: nums = [1,1,1,3,3,4,3,2,4,2]
Output: true

 

Constraints:

  • 1 <= nums.length <= 105
  • -109 <= nums[i] <= 109

Solution

contains-duplicate.py
class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        s = set()

        for x in nums:
            if x in s: return True
            s.add(x)

        return False