107. Binary Tree Level Order Traversal II刷题笔记

问题描述 自底向上层序搜索
python代码

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def levelOrderBottom(self, root: Optional[TreeNode]) -> List[List[int]]:
        result = []
        
        def BottomOrder(node,depth):
            if node:
                if depth==len(result):
                    result.insert(0,[])
                result[-1-depth].append(node.val)
                BottomOrder(node.left,depth+1)
                BottomOrder(node.right,depth+1)
        BottomOrder(root,0)
        return result

运行结果：