107. Binary Tree Level Order Traversal II Medium

1/**
2 * [107] Binary Tree Level Order Traversal II
3 *
4 * Given the root of a binary tree, return the bottom-up level order traversal of its nodes' values. (i.e., from left to right, level by level from leaf to root).
5 *  
6 * Example 1:
7 * <img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/tree1.jpg" style="width: 277px; height: 302px;" />
8 * Input: root = [3,9,20,null,null,15,7]
9 * Output: [[15,7],[9,20],[3]]
10 * 
11 * Example 2:
12 * 
13 * Input: root = [1]
14 * Output: [[1]]
15 * 
16 * Example 3:
17 * 
18 * Input: root = []
19 * Output: []
20 * 
21 *  
22 * Constraints:
23 * 
24 * 	The number of nodes in the tree is in the range [0, 2000].
25 * 	-1000 <= Node.val <= 1000
26 * 
27 */
28pub struct Solution {}
29use crate::util::tree::{TreeNode, to_tree};
30
31// problem: https://leetcode.com/problems/binary-tree-level-order-traversal-ii/
32// discuss: https://leetcode.com/problems/binary-tree-level-order-traversal-ii/discuss/?currentPage=1&orderBy=most_votes&query=
33
34// submission codes start here
35
36// Definition for a binary tree node.
37// #[derive(Debug, PartialEq, Eq)]
38// pub struct TreeNode {
39//   pub val: i32,
40//   pub left: Option<Rc<RefCell<TreeNode>>>,
41//   pub right: Option<Rc<RefCell<TreeNode>>>,
42// }
43// 
44// impl TreeNode {
45//   #[inline]
46//   pub fn new(val: i32) -> Self {
47//     TreeNode {
48//       val,
49//       left: None,
50//       right: None
51//     }
52//   }
53// }
54use std::rc::Rc;
55use std::cell::RefCell;
56impl Solution {
57    pub fn level_order_bottom(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<Vec<i32>> {
58        vec![]
59    }
60}
61
62// submission codes end
63
64#[cfg(test)]
65mod tests {
66    use super::*;
67
68    #[test]
69    fn test_107() {
70    }
71}
72