107. Binary Tree Level Order Traversal II
Medium
30 Points
Tree
Breadth-First Search
Binary Tree
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).
Examples
Example 1
Input: root = [3,9,20,null,null,15,7]
Output: [[15,7],[9,20],[3]]
Example 2
Input: root = [1]
Output: [[1]]
Example 3
Input: root = []
Output: []
Constraints
The number of nodes in the tree is in the range [0, 2000].-1000 <= Node.val <= 1000
107. Binary Tree Level Order Traversal II
Medium
30 Points
Tree
Breadth-First Search
Binary Tree
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).
Examples
Example 1
Input: root = [3,9,20,null,null,15,7]
Output: [[15,7],[9,20],[3]]
Example 2
Input: root = [1]
Output: [[1]]
Example 3
Input: root = []
Output: []
Constraints
The number of nodes in the tree is in the range [0, 2000].-1000 <= Node.val <= 1000