1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51

#![allow(dead_code)]

pub fn intersect(nums1: Vec<i32>, nums2: Vec<i32>) -> Vec<i32> {
    use std::collections::HashMap;

    if nums1.is_empty() || nums2.is_empty() {
        return vec![];
    }
    let mut map: HashMap<i32, i32> = HashMap::new();
    let mut res = vec![];
    for num in nums1 {
        match map.get_mut(&num) {
            Some(v) => {
                *v += 1;
            }
            None => {
                map.insert(num, 1);
            }
        }
    }

    for num in nums2 {
        match map.get_mut(&num) {
            Some(v) => {
                if *v > 0 {
                    *v -= 1;
                    res.push(num);
                }
            }

            None => {}
        }
    }
    res
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test1() {
        let nums1 = vec![1, 2, 2, 1];
        let nums2 = vec![2, 2];
        assert_eq!(intersect(nums1, nums2), vec![2, 2]);

        let nums1 = vec![4, 9, 5];
        let nums2 = vec![9, 4, 9, 8, 4];
        assert_eq!(intersect(nums1, nums2), vec![9, 4]);
    }
}