rust/src/binary_search_tree.rs

#![allow(dead_code)]

#[derive(Debug)]
struct Node {
    val: i32,
    left: Option<Box<Node>>,
    right: Option<Box<Node>>,
}

impl Node {
    fn new(val: i32) -> Self {
        Node { val, left: None, right: None }
    }
}

fn insert(root: Option<Box<Node>>, val: i32) -> Option<Box<Node>> {
    match root {
        None => Some(Box::new(Node::new(val))),
        Some(mut node) => {
            if val < node.val {
                node.left = insert(node.left, val);
            } else {
                node.right = insert(node.right, val);
            }
            Some(node)
        }
    }
}

fn inorder(root: &Option<Box<Node>>) {
    if let Some(node) = root {
        inorder(&node.left);
        println!("{}", node.val);
        inorder(&node.right);
    }
}

fn main() {
    let mut root = None;
    root = insert(root, 50);
    root = insert(root, 30);
    root = insert(root, 20);
    root = insert(root, 40);
    root = insert(root, 70);
    root = insert(root, 60);
    root = insert(root, 80);

    inorder(&root);
}