350. 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?

解法一：
Language-Java Run Time-3ms

public class Solution {    public int[] intersect(int[] nums1, int[] nums2) {        Arrays.sort(nums1);        Arrays.sort(nums2);        int i = 0;        int j = 0;        int count = 0;        int result[] =new int[Math.min(nums1.length, nums2.length)];        while(i < nums1.length && j < nums2.length)        {           if(nums1[i] == nums2[j]){               result[count++] = nums1[i];               i ++;               j ++;           }else if(nums1[i] < nums2[j]){               i ++;           }else{               j ++;           }        }        //复制指定的数组，截取或用 0 填充（如有必要），以使副本具有指定的长度        return Arrays.copyOf(result, count);    }}