Duplicate integer

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Problem

• Given an integer array nums, return true if any value appears more than once in the array, otherwise return false.

Example:

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

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Approach 1:

• Since a hash map can’t have duplicate values we can iterate through the original array and check if the current num is in the set, if not then add it to the set.

Implementation

class Solution:
    def hasDuplicate(self, nums: List[int]) -> bool:
        nonDuplicates = set()
        for num in nums:
            if num in nonDuplicates:
                return True
            seen.add(num)
        return False

Complexity Analysis

• Time Complexity: $O(n)$
• Space Complexity: $O(n)$