LeetCode41|数组中数组出现的次数

输入：nums = [4,1,4,6]
输出：[1,6] 或 [6,1]

import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

public class SingleNumbersTest {
    public static void main(String[] args) {
        int[] nums = {4, 1, 4, 6};
        int[] singleNumbers = singleNumbers(nums);
        for (int num : singleNumbers
        ) {
            System.out.print(num + "\t");
        }
    }

    public static int[] singleNumbers(int[] nums) {
        if (nums == null || nums.length == 0) {
            return new int[0];
        }
        int[] array = new int[10001];
        for (Integer num : nums
        ) {
            array[num]++;
        }
        int[] results = new int[2];
        int length = array.length;
        int j = 0;
        for (int i = 0; i < length; i++) {
            if (array[i] == 1) {
                results[j] = i;
                j++;
            }
        }
        return results;
    }

    public static int[] singleNumbers2(int[] nums) {
        if (nums == null || nums.length == 0) {
            return new int[0];
        }
        HashMap<Integer, Integer> hashMap = new HashMap<>(nums.length);
        for (int num : nums) {
            hashMap.put(num, hashMap.getOrDefault(num, 0) + 1);
        }
        List<Integer> list = hashMap.entrySet().stream().filter(x -> x.getValue() == 1)
                .collect(Collectors.toList()).stream().map(Map.Entry::getKey).collect(Collectors.toList());
        int[] results = new int[2];
        for (int i = 0, size = list.size(); i < size; i++) {
            results[i] = list.get(i);
        }
        return results;
    }

    public static int[] singleNumbers3(int[] nums) {
        if (nums == null || nums.length == 0) {
            return new int[0];
        }
        HashSet<Integer> hashSet = new HashSet<>();
        for (int num : nums) {
            if (hashSet.contains(num)) {
                hashSet.remove(num);
            } else {
                hashSet.add(num);
            }
        }
        return hashSet.stream().mapToInt(Integer::intValue).toArray();
    }
}