## 350. Intersection of Two Arrays II

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

Example 1:

```Input: nums1 = [1,2,2,1], nums2 = [2,2]
Output: [2,2]
```

Example 2:

```Input: nums1 = [4,9,5], nums2 = [9,4,9,8,4]
Output: [4,9]```

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?

## Rust Solution

``````struct Solution;

use std::collections::HashMap;
use std::collections::HashSet;

impl Solution {
fn intersect(nums1: Vec<i32>, nums2: Vec<i32>) -> Vec<i32> {
let mut hm1: HashMap<i32, i32> = HashMap::new();
let hs1: HashSet<i32> = nums1.clone().into_iter().collect();
nums1.iter().for_each(|&x| {
*hm1.entry(x).or_default() += 1;
});
let mut hm2: HashMap<i32, i32> = HashMap::new();
let hs2: HashSet<i32> = nums2.clone().into_iter().collect();
nums2.iter().for_each(|&x| {
*hm2.entry(x).or_default() += 1;
});
let bitand = &hs1 & &hs2;
let mut res: Vec<i32> = vec![];
bitand.iter().for_each(|&x| {
let c1 = hm1[&x];
let c2 = hm2[&x];
let min = i32::min(c1, c2);
(0..min).for_each(|_| {
res.push(x);
});
});
res
}
}

#[test]
fn test() {
let nums1 = vec![1, 2, 2, 1];
let nums2 = vec![2, 2];
assert_eq!(Solution::intersect(nums1, nums2), vec![2, 2]);
}
``````

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