0217: Contains Duplicate

Problem Statement

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

Explanation:

The element 1 occurs at the indices 0 and 3.

Example 2:

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

Output: false

Explanation:

All elements are distinct.

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

Code Solution

class Solution:
    def containsDuplicate(self, nums):
        cache = set()
        for n in nums:
            if n in cache:
                return True
            cache.add(n)
        return False