#[derive(Debug, PartialEq, Eq)]
pub struct TreeNode {
  pub val: i32,
  pub left: Option<Rc<RefCell<TreeNode>>>,
  pub right: Option<Rc<RefCell<TreeNode>>>,
}

impl TreeNode {
  #[inline]
  pub fn new(val: i32) -> Self {
    TreeNode {
      val,
      left: None,
      right: None
    }
  }
}
use std::rc::Rc;
use std::cell::RefCell;
pub fn merge_trees(t1: Option<Rc<RefCell<TreeNode>>>, t2: Option<Rc<RefCell<TreeNode>>>) -> Option<Rc<RefCell<TreeNode>>> {
	if let None = t1 {
		return t2;
	}
	if let None = t2 {
		return t1;
	}
	let t11 = t1.unwrap();
	let t22 = t2.unwrap();
	let t1_val = t11.borrow().val;
	let t2_val = t22.borrow().val;
	let mut t1_left = None;
	let mut t1_right = None;
	let mut t2_left = None;
	let mut t2_right = None;
	if let &Some(ref t) = &t11.borrow().left {
		t1_left = Some(Rc::clone(t));
	}
	if let &Some(ref t) = &t11.borrow().right {
		t1_right = Some(Rc::clone(t));
	}
	if let &Some(ref t) = &t22.borrow().left {
		t2_left = Some(Rc::clone(t));
	}
	if let &Some(ref t) = &t22.borrow().right {
		t2_right = Some(Rc::clone(t));
	}

	let left = merge_trees(t1_left, t2_left);
	let right = merge_trees(t1_right, t2_right);

	Some(Rc::new(RefCell::new(TreeNode {
		val: t1_val + t2_val,
		left: left,
		right: right,
	})))
}

fn main() {
    let t1 = Rc::new(RefCell::new(TreeNode::new(0)));
    t1.borrow_mut().left = Some(Rc::new(RefCell::new(TreeNode::new(1))));
    t1.borrow_mut().right = Some(Rc::new(RefCell::new(TreeNode::new(2))));
    let t2 = Rc::new(RefCell::new(TreeNode::new(3)));
    println!("merge_tree:{:?}", merge_trees(Some(t1), Some(t2)));
}