/**
 * [226] Invert Binary Tree
 */
pub struct Solution {}

use crate::util::tree::{to_tree, TreeNode};

// submission codes start here

// Definition for a binary tree node.
// #[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::cell::RefCell;
use std::rc::Rc;
impl Solution {
    pub fn invert_tree(root: Option<Rc<RefCell<TreeNode>>>) -> Option<Rc<RefCell<TreeNode>>> {
        match root {
            None => None,
            Some(root) => {
                let left = Self::invert_tree(root.borrow_mut().left.take());
                let right = Self::invert_tree(root.borrow_mut().right.take());

                root.borrow_mut().left = right;
                root.borrow_mut().right = left;

                Some(root)
            }
        }
    }
}

// submission codes end

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_226() {
        Solution::invert_tree(tree![2, 1, 3]);
    }
}