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 r…

题目: 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. 题解: 递归求解. 取当前点和左右边加和,当前点的值中最大的作为本层返回值.并在全局维护一个max.使用数组,因为是引用类型.所以在递归过程中可以保存结果. 代码如下:…

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 exampl…

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. Summary: DP, calucate the minimun…

Problem Description: http://oj.leetcode.com/problems/path-sum/ Pretty easy. /** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solu…

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. 题目大意:给定一个m*n矩阵,都是非负数字,找到一条路径从左上角到…

题目: 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. 题解: 这道题跟Unique Path系列是思路一样的.具…

题目: 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…

a(i):在节点i由于单边路径的最大结束 b(i):在节点i路径和 a(i) = max{ i->val, i->val + max{a(i->left), a(i->right) }}; b(i) = max{ i->val, i->val + max{a(i->left), a(i->right) } , i->val + a(i->left) + a(i->right)}; 因为a(i), b(i)只和a(i->left)和a(…

题目链接:Path Sum | LeetCode OJ 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…