023rd_box.rs

#![allow(unused)]

use std::fmt::Display;
use std::io;
use rand::Rng;
use std::io::{Write, BufReader, BufRead, ErrorKind};
use std::fs::File;
use std::cmp::Ordering;
use std::ops::Add; //for generic
use std::collections::HashMap; //for HashMap

fn main() {
    // smart pointers, box
    let b_int1 = Box::new(10);
    println!("b_int1 = {}", b_int1);

    struct TreeNode<T> {
        pub left: Option<Box<TreeNode<T>>>,
        pub right: Option<Box<TreeNode<T>>>,
        pub key: T, 
    }
    impl<T> TreeNode<T> {
        pub fn new(key: T) -> Self {
            TreeNode { left: None, right: None, key,
            }
        }
        pub fn left(mut self, node: TreeNode<T>) -> Self {
            self.left = Some(box::new(node));
            self
        }
        pub fn right(mut self, node: TreeNode<T>) -> Self {
            self.right = Some(box::new(node)); 
            self
        }
    }

    let node1 = TreeNode::new(1)
    .left(TreeNode::new(2)).right(TreeNode::new(3));


}