JAVA取数两个数组交集，考虑重复和不重复元素

import java.awt.List;
import java.util.ArrayList;
import java.util.TreeSet;
public class Solution {
     public static int[] intersection(int[] nums1,int[] nums2){
    	TreeSet<Integer> set =new TreeSet<>();
    	for(int num : nums1)//把不重复的nums1加入到集合中
    		set.add(num);
    	ArrayList<Integer> list=new ArrayList<>();
    	for(int num:nums2){
    		if(set.contains(num)){
    			list.add(num);
    			set.remove(num);
    		}	
    	}
    	int[] res=new int[list.size()]
    			
    			
    	for(int i=0;i<list.size();i++)
    		res[i]=list.get(i);
    	return res;
     }
     public static void main(String[] args) {
    	 int[] nums1={1,2,2,1};
    	 int[] nums2={2,2};
    	 System.out.println("shuju"+intersection(nums1,nums2));
     }
}

import java.util.ArrayList;
import java.util.TreeMap;

public class Solution1 {
	public static int[] intersect(int[] nums1, int[] nums2) {
		TreeMap<Integer, Integer> map = new TreeMap<>();
		for (int num : nums1) {
			if (!map.containsKey(num)) // 不包含
				map.put(num, 1); // 出现频率
			else
				map.put(num, map.get(num) - 1);
		}
		ArrayList<Integer> list = new ArrayList<>();
		for (int num : nums2) {
			if (map.containsKey(num)) {
				list.add(num);
				map.put(num, map.get(num) - 1);
				if (map.get(num) == 0)
					map.remove(num);
			}
		}
		int[] res = new int[list.size()];
		for (int i = 0; i < list.size(); i++)
			res[i] = list.get(i);
		return res;
	}
}