说白了这道题的难点就是如何求每一层的结点值之和,肯定需要遍历整个二叉树,用什么样的遍历方式呢,当然是用层序最方便啦,LeetCode 中有考察层序遍历的题,Binary Tree Level Order Traversal和 Binary Tree Level Order Traversal II,做过这两道的话,这道题也就没啥难度了。这里还是用 queue 来辅助遍
Given therootof a binary tree, the level of its root is1, the level of its children is2, and so on. Return the smallest levelXsuch that the sum of all the values of nodes at levelXis maximal. Example 1: Input:[1,7,0,7,-8,null,null] Output:2 Explanation: Level 1 sum = 1. ...
# 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 rangeSumBST(self, root: Optional[TreeNode], low: int, high: int) -> int: # 如果 roo...
Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example: Given the below binary tree andsum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1 1. 2. 3. 4. 5. 6. ...
Can you solve this real interview question? Binary Search Tree to Greater Sum Tree - Given the root of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus the sum of all key
Given a binary tree, find the maximum path sum. The path may start and end at any node in the tree. For example: Given the below binary tree, 1 / \ 2 3 1. 2. 3. Return6. 题意: 给定一棵二叉树,找出最大得路径和。 路径的起始和结束位置能够是树中的随意节点。
http://www.programcreek.com/2013/02/leetcode-binary-tree-maximum-path-sum-java/ 另外,这道题目的BST条件,似乎没什么用。因为如果全是负数,BST也没帮助了。 ** 总结: pre-order -> top-down post-order -> bottom-up in-order -> ? level-order -> bfs ...
方法2是Leetcode上的Solution,思路是先初始化了一个self.ans为0,然后逐个遍历节点,每遇到一个在[L,R]内的节点,就做一次加法累进self.ans。 具体的做法: 判断当前节点是否在[L,R]内,在的话self.ans加上当前节点值,不在的话继续步骤2和3 判断左子树是否可能存在符合要求的节点。根据二叉搜索树定义,左子树中...
code 代码语言:javascript 代码运行次数:0 运行 AI代码解释 type TreeNode struct { Val int Left *TreeNode Right *TreeNode } var ret int func sumRootToLeaf(root *TreeNode) int { ret = 0 helper(root, 0) return ret } func helper(root *TreeNode, sum int) { if root == nil { return ...
:pencil2: 算法相关知识储备 LeetCode with Python :books:. Contribute to jmfu95/leetCode development by creating an account on GitHub.