第一选择是将其转化成图用动态规划,但这样还是太麻烦 使用递归的思路,对于当前的节点root,分别求左右孩子到当前节点的单项路径权值最大的路径权值,然后记包含当前节点的路径权值为 path_price=root->val+left_gain+right_gain,取sum_max和他较大的: 返回左右孩子权值最大的单向路径(只往上不拐弯)的权值(这需要好好理解,因为更新权值的式子是root->val+left_gain+right_gain,即从左子路到根再到右子路的一条式子,所以计算left_…

You are given a binary tree in which each node contains an integer value. Find the number of paths that sum to a given value. The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to…

If the depth of a tree is smaller than 5, then this tree can be represented by a list of three-digits integers. For each integer in this list: The hundreds digit represents the depth D of this node, 1 <= D <= 4. The tens digit represents the positio…

二叉树的路径和 给定一个二叉树,找出所有路径中各节点相加总和等于给定 目标值 的路径. 一个有效的路径,指的是从根节点到叶节点的路径. 样例 给定一个二叉树,和 目标值 = 5: 返回: [     [1, 2, 2],     [1, 4] ] 标签 二叉树 二叉树遍历 code /** * Definition of TreeNode: * class TreeNode { * public: * int val; * TreeNode *left, *right; * TreeNode(i…

题: 解: 这道题考的是如何找出一个二叉树里所有的序列. 我的思路是先从根节点开始遍历,找出所有的子节点,因为每个子节点只有一个父节点,再根据每个子节点向上遍历找出所有的序列,再判断序列的总和. 这样解效率不高,但暂时只能想到这样.如果您有其余的解法,期望告知. 代码: package com.lintcode; import java.util.ArrayList; import java.util.Collections; import java.util.Enumeration; impo…

If the depth of a tree is smaller than 5, then this tree can be represented by a list of three-digits integers. For each integer in this list: The hundreds digit represents the depth D of this node, 1 <= D <= 4. The tens digit represents the positio…

Given a non-empty binary tree, find the maximum path sum. For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The path must contain at least one node and doe…

(没做出来,典型题目重要) 二叉树中的最大路径和(hard) 给定一个非空二叉树,返回其最大路径和. 本题中,路径被定义为一条从树中任意节点出发,达到任意节点的序列.该路径至少包含一个节点,且不一定经过根节点. 示例 1: 输入: [1,2,3] 1 / \ 2 3 输出: 6 示例 2: 输入: [-10,9,20,null,null,15,7]   -10    / \   9  20     /  \    15   7 输出: 42 关键点:1.和求根节点到叶节点的最长路径的题目一样(最…

给定一个非空二叉树,返回其最大路径和. 本题中,路径被定义为一条从树中任意节点出发,达到任意节点的序列.该路径至少包含一个节点,且不一定经过根节点. 示例 1: 输入: [1,2,3] 1 / \ 2 3 输出: 6 示例 2: 输入: [-10,9,20,null,null,15,7] -10 / \ 9 20 / \ 15 7 输出: 42 /** * Definition for a binary tree node. * public class TreeNode { * int val…

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 and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1 return true…