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…

Leetcode之动态规划(DP)专题-64. 最小路径和(Minimum Path Sum) 给定一个包含非负整数的 m x n 网格,请找出一条从左上角到右下角的路径,使得路径上的数字总和为最小. 说明:每次只能向下或者向右移动一步. 示例: 输入: [   [1,3,1], [1,5,1], [4,2,1] ] 输出: 7 解释: 因为路径 1→3→1→1→1 的总和最小. 找从左上角0,0到右下角的最短路径. DP:我们每个点(x,y)都可以表示为dp[x][y] = max( grid…

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…

题目 给定一个二叉树和一个目标和,找到所有从根节点到叶子节点路径总和等于给定目标和的路径. 说明: 叶子节点是指没有子节点的节点. 示例: 给定如下二叉树,以及目标和 sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 返回: [ [5,4,11,2], [5,8,4,5] ] 本题同[剑指Offer]面试题34. 二叉树中和为某一值的路径 思路一:回溯 代码 class Solution { public: vector<vector<int&…

LeetCode:Path Sum 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 / \ \…

Path Sum 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 re…

1.  Path Sum 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…

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. The path does not need to go through the root. For exa…

Path Sum I 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. Note: A leaf is a node with no children. Example: Given the below binary tree and sum = 22…

  I 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…