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qmzp's questions

Martin Hope
qmzp
Asked: 2025-01-13 14:09:17 +0800 CST
  • 4

Este é meu código de lista encadeada simples, ainda tenho que implementar as funções pop from end e pop from front, mas estou tendo dificuldade em escrever a função pop from end

#![allow(warnings)]

#[derive(Clone)]
struct List {
    el: i32,
    next: Box<Option<List>>
}

impl List {
    fn new(val: i32) -> List {
        return List {
            el: val,
            next: Box::new(None)
        }
    }

    fn from(arr: &[i32]) -> List {
        let mut head = List::new(arr[0]);

        let mut current = &mut head;
        for &val in &arr[1..] {
            /* current.next = Box::new(Some(List::new(val)));
            current = (*current.next).as_mut().unwrap(); */
            current.append(val);
        }
        return head
    }

    fn append(&mut self, val: i32) {
        let mut current = self;
        while let Some(ref mut next_node) = *current.next {
            current = next_node;
        }
        current.next = Box::new(Some(List::new(val)));
    }

    fn prepend(&mut self, val:i32) {
        // std::mem::replace(dest, src): 
        //    Moves src into the referenced dest, returning the previous dest value
        let old_self = std::mem::replace(self, List::new(val));
        self.next = Box::new(Some(old_self));
    }
}

fn main() {
    let mut list = List::new(42);
    list.append(32);
    list.append(2321);
    list.append(2839);
    list.prepend(69);
    list.pop(); // 2839 // difficulty in implementing this
    println!("{}", list);

    let mut list = List::from(&[1, 2, 3]);
    list.prepend(0);
    println!("{}", list);
}

Devo usar Rce RefCellimplementar uma lista encadeada única? Sou iniciante, então, por favor, ajude. Obrigado!

rust