217. Contains Duplicate ✅

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

Solution:

class Solution {
    public boolean containsDuplicate(int[] nums) {
        Set<Integer> set = new HashSet<Integer>();
        for (int i = 0; i < nums.length; i++){
            if (set.contains(nums[i])){
                return true;
            }
            set.add(nums[i]);
        }
        return false;
    }
}

// TC: O(n)
// SC: O(n)