rust_btree_box.rs

struct Node {
    data: i32,
    left: Option<Box<Node>>,
    right: Option<Box<Node>>,
}
fn add(tree:&mut Box<Node>, x: i32){ 
    if tree.data==x{
        return;         
    }
    let t=tree.data;
    let target_node = if x < t { &mut tree.left } else { &mut tree.right };
    match  target_node {
        Some(node)=>add(node, x),
        None=>{
            let new_node=Node{data:x,left:None,right:None};
            let boxed=Some(Box::new(new_node));
            *target_node=boxed;
        }
    }
}
fn travel(tree: &Box<Node>) {

    let l=tree.left.as_ref();
    if let Some(t)=l{
        travel(t);
    }
    println!("{}",tree.data);
    let r=tree.right.as_ref();
    if let Some(t)=r{
        travel(t);
    }   
}

fn main() {
    let node=Node{data:12,left:None,right:None};
    let mut tree=Box::new(node);
    let b=&mut tree;
    add(b, 200);
    add(b, 190);
    add(b, 213);
    add(b, 56);
    add(b, 24);
    add(b, 18);
    add(b, 27);
    add(b, 28);
    travel(&tree);
}