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.
Examples
Input:
nums = [1,2,3,1]Output:
trueExplanation:
Using a hash set to track seen values, This finds that 1 appears at index 0 and again at index 3, confirming a duplicate exists.
Input:
nums = [1,2,3,4]Output:
falseExplanation:
After checking all elements against a hash set, no value is encountered twice. Each of 1, 2, 3, and 4 appears exactly once, so no duplicate exists.
Input:
nums = [1,1,1,3,3,4,3,2,4,2]Output:
trueExplanation:
Multiple values repeat: 1 appears twice, 3 appears three times, 4 appears twice, and 2 appears twice. The algorithm returns true as soon as the first duplicate is detected.
Constraints
- •
1 ≤ nums.length ≤ 10⁵ - •
-10⁹ ≤ nums[i] ≤ 10⁹