Rust Brain Teasers

Puzzle 15

To Infinity

linked_list/src/main.rs

use std::cell::RefCell;
use std::rc::Rc;

type Link = Option<Rc<RefCell<Node>>>;

#[derive(Debug)]
struct Node {
    elem: i32,
    next: Link,
}

fn main() {
    let mut head = Some(Rc::new(
        RefCell::new(Node{ elem: 1, next: None })
    ));
    head
        .as_mut()
        .unwrap()
        .borrow_mut()
        .next = Some(Rc::new(RefCell::new(
            Node{ elem: 2, next: head.clone() })
        ));

    println!("{:?}", head);
}

Guess the Output
	Try to guess what the output is before moving to the next page.

The program will display node 1, node 2, and then node 1 again. ...