[Leetcode] Intersection of Two Arrays II

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

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

Note:

• Each element in the result should appear as many times as it shows in both arrays.
• The result can be in any order.

Follow up:

• What if the given array is already sorted? How would you optimize your algorithm?
• What if nums1's size is small compared to nums2's size? Which algorithm is better?

• What if elements of nums2 are stored on disk, and the memory is limited such that you cannot load all elements into the memory at once?

public class Solution {    public int[] intersect(int[] nums1, int[] nums2) {        ArrayList<Integer> list2 = new ArrayList<Integer>();        ArrayList<Integer> myList = new ArrayList<Integer>();        int len1=nums1.length;        int len2=nums2.length;        for(int i=0;i<len2;i++)        list2.add(nums2[i]);        for(int i=0;i<len1;i++)        {                    int j=list2.indexOf(nums1[i]);                    if(j==-1) continue;                    myList.add(nums1[i]);                    list2.remove(j);        }        int[] res = new int[myList.size()];        for(int i = 0; i<res.length; i++){            res[i] = (Integer)myList.get(i);        }        return res;    }}