217.contains-duplicate.java

/*
 * @lc app=leetcode id=217 lang=java
 *
 * [217] Contains Duplicate
 *
 * https://leetcode.com/problems/contains-duplicate/description/
 *
 * algorithms
 * Easy (56.60%)
 * Total Accepted:    749.2K
 * Total Submissions: 1.3M
 * Testcase Example:  '[1,2,3,1]'
 *
 * 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
 *
 */
class Solution {
	public boolean containsDuplicate(int[] nums) {

		HashSet<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;
	}
}