> For the complete documentation index, see [llms.txt](https://jaywin.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jaywin.gitbook.io/leetcode/solutions/0349-intersection-of-two-arrays.md).

# 0349. Intersection of Two Arrays

<https://leetcode.com/problems/intersection-of-two-arrays>

## Description

Given two integer arrays `nums1` and `nums2`, return *an array of their intersection*. Each element in the result must be **unique** and you may return the result in **any order**.

**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]
**Explanation:** [4,9] is also accepted.
```

**Constraints:**

* `1 <= nums1.length, nums2.length <= 1000`
* `0 <= nums1[i], nums2[i] <= 1000`

## ac

```java
class Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
        Set<Integer> set1 = new HashSet<Integer>();
        Set<Integer> set2 = new HashSet<Integer>();

        for (int n : nums1) {
            set1.add(n);
        }
        for (int n : nums2) {
            if (set1.contains(n)) set2.add(n);
        }

        int[] res = new int[set2.size()];
        int i = 0;
        for (int n : set2) {
            res[i++] = n;
        }

        return res;
    }
}
```