Leetcode-349: the intersection of two arrays

topic:

Given two arrays, write a function to calculate their intersection. Example 1:
Input: nums1 = [1,2,2,1], nums2 = [2,2]
Output: [2]
Example 2:
Input: nums1 = [4,9,5], nums2 = [9,4 ,9,8,4]
Output: [9,4]
Description:
Each element in the output result must be unique.
We can ignore the order of output results.

Code:

import java.util.*;
class Solution {
    
    
    public int[] intersection(int[] nums1, int[] nums2) {
    
    
        TreeSet<Integer> set=new TreeSet<>();
        for(int num:nums1){
    
    
            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;
    }
}