LeetCode: 217. Contains Duplicate

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217. Contains Duplicate

LeetCode - 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.

Example 1:

Input: [1,2,3,1]
Output: true

Example 2:

Input: [1,2,3,4]
Output: false

Example 3:

Input: [1,1,1,3,3,4,3,2,4,2]
Output: true

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/**
 * Runtime: 9 ms, faster than 58.06% of Java online submissions for Contains Duplicate.
 *
 * Memory Usage: 44.4 MB, less than 57.76% of Java online submissions for Contains Duplicate.
 */
public boolean containsDuplicate(int[] nums) {
    if (Objects.isNull(nums) || nums.length < 2) {
        return false;
    }
    Set<Integer> numSet = new HashSet<>();
    for (int num : nums) {
        if (numSet.contains(num)) {
            return true;
        } else {
            numSet.add(num);
        }
    }
    return false;
}

/**
 * Runtime: 5 ms, faster than 96.50% of Java online submissions for Contains Duplicate.
 *
 * Memory Usage: 42.1 MB, less than 98.28% of Java online submissions for Contains Duplicate.
 */
public boolean containsDuplicateSort(int[] nums) {
    if (Objects.isNull(nums) || nums.length < 2) {
        return false;
    }
    Arrays.sort(nums);
    for (int i = 0; i < nums.length - 1; i++) {
        if (nums[i] == nums[i + 1]) {
            return true;
        }
    }
    return false;
}