# 题目

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

Example 1:

Example 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.

• 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?

# 解答1[Java]

## 复杂度分析

HashMap 的 get() 时间复杂度为 $O(1)$。