首先要说明二叉树的问题就是用递归来做,基本没有其他方法,因为这数据结构基本只能用递归遍历,不要把事情想复杂了. #112 Path Sum 原题链接:https://leetcode.com/problems/path-sum/ . 判断从树的根节点到叶子节点的路径中,是否有一条所有节点上的值之和和特定的数字,即sum. 从根节点到叶子节点,线路的起点的是固定的,只需要不断递归下去,判断在叶子节点处是否满足根节点加到该节点的值之和为sum. 这个限制条件把这个问题简化了很多很多. /** * D…

112. 路径总和 112. Path Sum 题目描述 给定一个二叉树和一个目标和,判断该树中是否存在根节点到叶子节点的路径,这条路径上所有节点值相加等于目标和. 说明: 叶子节点是指没有子节点的节点. 每日一算法2019/5/13Day 10LeetCode112. Path Sum 示例: 给定如下二叉树,以及目标和 sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \ 7 2 1 返回 true,因为存在目标和为 22 的根节点到叶子节点的路径 5->4->1…

题目 Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example: Given the below binary tree and sum = 22, 分析 本题目与上一题LeetCode(112) Path Sum虽然类型相同,但是需要在以前的基础上,多做处理一些: 与Path Sum相比,本题是求出路径,所以,在找到满足的路…

112. Path Sum 自己的一个错误写法: class Solution { public: bool hasPathSum(TreeNode* root, int sum) { if(root == NULL) return false; ; return hasPathSum(root,sum,value); } bool hasPathSum(TreeNode* root,int sum,int value){ if(root == NULL){ if(value == sum) r…

437. Path Sum III 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 fro…

problem 437. Path Sum III 参考 1. Leetcode_437. Path Sum III; 完…

原题: 437. Path Sum III 解题: 思路1就是:以根节点开始遍历找到适合路径,以根节点的左孩子节点开始遍历,然后以根节点的右孩子节点开始遍历,不断循环,也就是以每个节点为起始遍历点 代码如下: class Solution { public: int pathSum(TreeNode* root, int sum) { if(!root) return 0; int count = getPath(root,0,sum) + pathSum(root->left,sum) + p…

Leetcode 931. Minimum falling path sum 最小下降路径和(动态规划) 题目描述 已知一个正方形二维数组A,我们想找到一条最小下降路径的和 所谓下降路径是指,从一行到下一行,只能选择间距不超过1的列(也就是说第一行的第一列,只能选择第二行的第一列和第二列:第二行的第二列,只能选择第三行的第一列第二列第三列),最小下降路径就是这个路径的和最小 测试样例 Input: [[1,2,3],[4,5,6],[7,8,9]] Output: 12 Explanation:…

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…

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…

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…

  相关问题:112 path sum /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: int pathSum(TreeNode* root, int s…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 DFS 回溯 BFS 栈 日期 题目地址:https://leetcode.com/problems/path-sum/#/description 题目描述 Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up…

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 Return 6. 这道求二叉树的最大路径和是一道蛮有难度的题,难就难在起始位置和结束位置可以为任意位置,我当然是又不会了,于是上网看看大神们的解法,看了很多人的都没太看明白,最后发现了网友Yu's…

1.题目说明 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 Return 6.   2.解法分析: leetcode中给出的函数头为:int maxPathSum(TreeNode *root) 给定的数据结构为: Definit…

偶然在面试题里面看到这个题所以就在Leetcode上找了一下,不过Leetcode上的比较简单一点. 题目: Given a 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. Th…

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 Return 6. 题目意思很简单,就是给定一棵二叉树,求最大路径和.path 可以从任意 node 开始,到任意 node 结束. 这道题在 LeetCode 上的通过率只有 20% 多一点,并被…

原题地址:https://oj.leetcode.com/problems/binary-tree-maximum-path-sum/ 题意: 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 Return 6. 解题思路:这道题是在树中寻找一条路…

原题链接在这里:https://leetcode.com/problems/minimum-falling-path-sum/ 题目: Given a square array of integers A, we want the minimum sum of a falling path through A. A falling path starts at any element in the first row, and chooses one element from each row.…

Given a square array of integers A, we want the minimum sum of a falling path through A. A falling path starts at any element in the first row, and chooses one element from each row.  The next row's choice must be in a column that is different from t…

Binary Tree Maximum Path Sum 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 Return 6. 递归求解. maxPathSum(root)跟maxPathSum(root.left)和maxPathSum(roo…

Minimum Path Sum Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only move either down or right at any point in time. 还是DP问题,给定一个m*n的二…

Path Sum 题目链接 题目要求: 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 /…

Binary Tree Maximum Path SumGiven 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 SOLUTION 1: 计算树的最长path有2种情况: 1. 通过根的path. (1)如果左子树从左树根到任何一个N…

Minimum Path Sum Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only move either down or right at any point in time. 解题思路: 典型的动态规划.开辟…

题目: Binary Tree Maximum Path Sum 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 Return 6. 节点可能为负数,寻找一条最路径使得所经过节点和最大.路径可以开始和结束于任何节点但是不能走回头路. 这道题虽然看…

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 Return6. 思路:题目中说明起始节点可以是任意节点,所以,最大的路径和不一样要经过root,可以是左子树中某一条,或者是右子树中某一条,当然也可能是经过树的根节点root的.递归式是应该是这三…

问题 给出一棵二叉树及一个和值,检查该树是否存在一条根到叶子的路径,该路径经过的所有节点值的和等于给出的和值. 例如, 给出以下二叉树及和值22: 5         / \       4  8      /   / \    11 13 4    / \        \  7   2        1 函数返回true,因为存在一条根到叶子的路径5->4->11->2,其路径和为22. 初始思路 鉴于题目要求找到一条路径和符合要求即可,选择层次遍历二叉树是一种比较合适的选择-保证了…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 DFS + DFS BFS + DFS 日期 题目地址:https://leetcode.com/problems/path-sum-iii/#/description 题目描述 You are given a binary tree in which each node contains an integer value. Find the num…

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…