Intersection of Two Arrays

Given two arrays, write a function to compute their intersection.

Example: Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2].

Note:

Each element in the result must be unique. The result can be in any order.

Solution

public class Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
                    if (nums1 == null || nums2 == null || nums1.length == 0 || nums2.length == 0) {
            return new int[0];
        }

        Set<Integer> result = new HashSet<>();
        Map<Integer, Integer> map = new HashMap<>();
        Arrays.stream(nums1).forEach(
                item -> {
                    map.merge(item, 1, (a, b) -> a + b);
                }
        );

        for (int num : nums2) {
            if (map.containsKey(num)) {
                result.add(num);
                map.merge(num, 1, (a, b) -> a - b);
                if (map.get(num) == 0) {
                    map.remove(num);
                }
            }
        }

        List<Integer> result1 = result.stream().collect(Collectors.toList());
        int[] resultArray = new int[result.size()];
        for (int i = 0; i < result.size(); i++) {
            resultArray[i] = result1.get(i);
        }

        return resultArray;
    }
}