LeetCode-in-Java

217. Contains Duplicate

Easy

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

import java.util.HashSet;
import java.util.Set;

public class Solution {
    public boolean containsDuplicate(int[] nums) {
        Set<Integer> set = new HashSet<>();
        for (int n : nums) {
            if (set.contains(n)) {
                return true;
            }
            set.add(n);
        }
        return false;
    }
}

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