Arrays & Hashing - Contains Duplicate

Contains Duplicate

Problem information

Leedcode problem: https://leetcode.coqm/problems/contains-duplicate/
Neetcode problem: https://neetcode.io/problems/duplicate-integer
Difficulty: Easy

Solution

Use a HashSet to insert and check if the set contains a given number in constant time.

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

class Solution {
    public boolean hasDuplicate(int[] nums) {
        Set<Integer> set = new HashSet<>();

        for (int num: nums) {
            if (set.contains(num)) {
                return true;
            }

            set.add(num);
        }

        return false;
    }
}