349. Intersection of Two Arrays

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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.

public int[] intersection(int[] nums1, int[] nums2) {        Map<Integer, Integer> map = new HashMap<>();        Arrays.sort(nums1);        Arrays.sort(nums2);        for (int i = 0; i < nums1.length; i++) {            binarySearch(nums2, nums1[i], 0, nums2.length - 1, map);        }        Set keys = map.keySet();        int[] key = new int[keys.size()];        Iterator it = keys.iterator();        for (int i = 0; i < keys.size(); i++) {            key[i] = (int)it.next();        }        return key;    }    public void binarySearch(int[] nums, int findNum, int start, int end, Map<Integer, Integer> map) {        if (start < end) {            int middle = (end - start) / 2 + start;            if (nums[middle] > findNum) {                binarySearch(nums, findNum, start, middle - 1, map);            } else if (nums[middle] < findNum) {                binarySearch(nums, findNum, middle + 1, end, map);            } else {                map.put(findNum, middle);            }        } else if (start == end) {            if (nums[start] == findNum) {                map.put(findNum, start);            }        }    }

要用二叉搜索先排序。