design-hashmap/src/main.rs


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fn main() {
    println!("Hello, world!");
    let mut a = MyHashMap::new();
    a.put(1,1);
    a.put(2,2);
    a.get(1);
    a.get(3);
    a.put(2,1);
    a.get(2);
    a.remove(2);
    a.get(2);
}

struct MyHashMap {
    map: Vec<(i32,i32)>
}

impl MyHashMap {

    fn new() -> Self {
        MyHashMap {
            map: Vec::new()
        }       
    }
    
    fn put(&mut self, key: i32, value: i32) {
        match self.map.iter_mut().find(|x| x.0 == key) {
            Some(e) => e.1 = value,
            None => self.map.push((key, value))
        };
    }
    
    fn get(&self, key: i32) -> i32 {
        self.map.iter().find(|&x| x.0 == key).map(|x| x.1).unwrap_or(-1)
    }
    
    fn remove(&mut self, key: i32) {
        if let Some(e) = self.map.iter().position(|x| x.0 == key) {
            self.map.swap_remove(e);
        }
    }
}