350. Intersection of Two Arrays II

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

题目含义z:计算两个数组的交集,重复的数字要保留

    public int[] intersect(int[] nums1, int[] nums2) {
        if (nums1.length == 0 || nums2.length == 0) return new int[0];
        Map<Integer, Integer> numberMap = new HashMap<>();
        for (int i = 0; i < nums1.length; i++)
            numberMap.put(nums1[i], numberMap.getOrDefault(nums1[i], 0) + 1);
        List<Integer> resultList = new ArrayList<Integer>();
        for (int i = 0; i < nums2.length; i++) {
            if (numberMap.containsKey(nums2[i]) && numberMap.get(nums2[i]) > 0) {
                resultList.add(nums2[i]);
                numberMap.put(nums2[i], numberMap.get(nums2[i]) - 1);
            }
        }
        int[] result = new int[resultList.size()];
        for (int i = 0; i < result.length; i++) result[i] = resultList.get(i);
        return result;        
    }