LeetCode_217. Contains Duplicate

package leetcode.easy;

public class ContainsDuplicate {
	public boolean containsDuplicate1(int[] nums) {
		for (int i = 0; i < nums.length; ++i) {
			for (int j = 0; j < i; ++j) {
				if (nums[j] == nums[i]) {
					return true;
				}
			}
		}
		return false;
	}
	// Time Limit Exceeded

	public boolean containsDuplicate2(int[] nums) {
		java.util.Arrays.sort(nums);
		for (int i = 0; i < nums.length - 1; ++i) {
			if (nums[i] == nums[i + 1]) {
				return true;
			}
		}
		return false;
	}

	public boolean containsDuplicate3(int[] nums) {
		java.util.Set<Integer> set = new java.util.HashSet<>(nums.length);
		for (int x : nums) {
			if (set.contains(x)) {
				return true;
			} else {
				set.add(x);
			}
		}
		return false;
	}

	@org.junit.Test
	public void test1() {
		int[] nums1 = { 1, 2, 3, 1 };
		int[] nums2 = { 1, 2, 3, 4 };
		int[] nums3 = { 1, 1, 1, 3, 3, 4, 3, 2, 4, 2 };
		System.out.println(containsDuplicate1(nums1));
		System.out.println(containsDuplicate1(nums2));
		System.out.println(containsDuplicate1(nums3));
	}

	@org.junit.Test
	public void test2() {
		int[] nums1 = { 1, 2, 3, 1 };
		int[] nums2 = { 1, 2, 3, 4 };
		int[] nums3 = { 1, 1, 1, 3, 3, 4, 3, 2, 4, 2 };
		System.out.println(containsDuplicate2(nums1));
		System.out.println(containsDuplicate2(nums2));
		System.out.println(containsDuplicate2(nums3));
	}

	@org.junit.Test
	public void test3() {
		int[] nums1 = { 1, 2, 3, 1 };
		int[] nums2 = { 1, 2, 3, 4 };
		int[] nums3 = { 1, 1, 1, 3, 3, 4, 3, 2, 4, 2 };
		System.out.println(containsDuplicate3(nums1));
		System.out.println(containsDuplicate3(nums2));
		System.out.println(containsDuplicate3(nums3));
	}
}