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use std::{cell::RefCell, rc::Rc};
pub struct Solution;
#[derive(Debug, PartialEq, Eq)]
pub struct TreeNode {
pub val: i32,
pub left: Option<Rc<RefCell<TreeNode>>>,
pub right: Option<Rc<RefCell<TreeNode>>>,
}
#[allow(unused)]
impl TreeNode {
#[inline]
pub fn new(val: i32) -> Self {
TreeNode { val, left: None, right: None }
}
}
#[allow(unused)]
impl Solution {
pub fn level_order(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<Vec<i32>> {
let mut res = vec![];
if root.is_none() {
return res
}
let mut queue = vec![root.unwrap()]; let mut height = 0;
while !queue.is_empty() {
height += 1;
let mut tmp = vec![]; let mut tmp_res = std::collections::VecDeque::new(); for node in queue {
let n1 = node.borrow();
if height % 2 == 1 {
tmp_res.push_back(n1.val);
} else {
tmp_res.push_front(n1.val);
}
if n1.left.is_some() {
tmp.push(n1.left.clone().unwrap());
}
if n1.right.is_some() {
tmp.push(n1.right.clone().unwrap());
}
}
let this_res = tmp_res.into_iter().collect::<Vec<i32>>();
res.push(this_res);
queue = tmp;
}
res
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
let root = Some(Rc::new(RefCell::new(TreeNode {
val: 3,
left: Some(Rc::new(RefCell::new(TreeNode { val: 9, left: None, right: None }))),
right: Some(Rc::new(RefCell::new(TreeNode {
val: 20,
left: Some(Rc::new(RefCell::new(TreeNode { val: 15, left: None, right: None }))),
right: Some(Rc::new(RefCell::new(TreeNode { val: 7, left: None, right: None }))),
}))),
})));
assert_eq!(Solution::level_order(root), vec![vec![3], vec![20, 9], vec![15, 7]]);
}
}