[LeetCode] 217. Contains Duplicate

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

 Thought process:
Iterate through the array. Use a set to keep track of numbers seen.

 Solution 1:
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public class Solution {
    public boolean containsDuplicate(int[] nums) {
        Set<Integer> set = new HashSet<>();
        
        for (int num : nums) {
            if (set.contains(num)) {
                return true;
            }
            set.add(num);
        }
        
        return false;
    }
}

Time complexity: O(n).

 And a functional Java solution just for fun (beats 0.14% of Java submissions).

 Solution 2:
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public class Solution {
    public boolean containsDuplicate(int[] nums) {
        return nums.length != Arrays.stream(nums).distinct().count();
    }
}

Time complexity: unknown.
Location: San Jose, CA, USA

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