令$a_{i}$为$i$的度数-1,那么$(x,s)$合法即等价于存在$S\subseteq [1,n],|S|=x$且$\sum_{k\in S}a_{k}=s$ 引理:$(x,s)$合法的必要条件为$-z\le s-x\le z-2$ 令$z$为$a_{i}$中为0的元素个数,考虑任意一个集合$S\subseteq [1,n]$,显然$-z\le \sum_{k\in S}a_{k}-|S|\le z-2$ 具体的,考虑该式即为$\sum_{k\in S}(a_{k}-1)$,那么将所有$a…

\(\mathcal{Description}\)   Link.   给定含有 \(n\) 个结点的树,求非负整数对 \((x,y)\) 的数量,满足存在 \(\exist S\subseteq V,~|S|=x\land\sum_{u\in S}d_u=y\),其中 \(d_u\) 表示点 \(u\) 的度数.   \(n\le2\times10^5\). \(\mathcal{Solution}\)   方便期间,以下所有 \(d_u\) 表示 \(u\) 的度数 \(-1\).   出题…

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…

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.   用递归确定每一个节点作为root时,从root出发的最长的路径 在每一次递归中计算maxPath   /** * D…

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. 思想: 后序遍历.注意路径的连通: 结点不为空时要返回  max( max(leftV, rightV)+rootV,…

https://en.wikipedia.org/wiki/Subset_sum_problem In computer science, the subset sum problem is an important problem in complexity theory and cryptography. The problem is this: given a set (or multiset) of integers, is there a non-empty subset whose…

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 return true…

  继续讲故事~~   上次讲到我们的主人公丁丁,用神奇的动态规划法解决了杂货店老板的两个找零钱问题,得到了老板的肯定.之后,他就决心去大城市闯荡了,看一看外面更大的世界.   这天,丁丁刚回到家,他的弟弟小连就拦住了他,"老哥,有个问题想请教你."对于一向数学见长的小连,这次竟然破天荒的来问自己问题,丁丁感到不可思议:他俩一个以计算机见长,一个以数学见长,各自心里都有点小骄傲,不会轻易地向对方问问题.丁丁迟疑了一会儿,慢慢说道:"有什么问题是我们数学小天才解决不了的?&qu…

124. Binary Tree Maximum Path Sum https://www.cnblogs.com/grandyang/p/4280120.html 如果你要计算加上当前节点的最大path和,这个节点的左右子树必定是纯左右树(即没有拐点), 用另一个参数保留整个二叉树的最大path和,然后计算每一个以当前节点为拐点的路径和并且不断更新整个二叉树的最大值 函数的返回值是纯左右子树的最大path,没有拐点 这个题目给root定位为非空,所以直接这样写可以.如果root为空,这样写就会…

Given a non-empty array containing only positive integers, find if the array can be partitioned into two subsets such that the sum of elements in both subsets is equal. Note: Each of the array element will not exceed 100. The array size will not exce…

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…

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. 树结构显然用递归来解,解题关键: 1.对于每一层递归,只有包含此层树根节点的值才可以返回到上层.否则路径将不连续. 2.…

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…

lc 416 Partition Equal Subset Sum 416 Partition Equal Subset Sum Given a non-empty array containing only positive integers, find if the array can be partitioned into two subsets such that the sum of elements in both subsets is equal. Note: Each of th…

124. Binary Tree Maximum Path Sum 题意:给定一个二叉树,每个节点有一个权值,寻找任意一个路径,使得权值和最大,只需返回权值和. 思路:对于每一个节点 首先考虑以这个节点为结尾(包含它或者不包含)的最大值,有两种情况,分别来自左儿子和右儿子设为Vnow. 然后考虑经过这个节点的情况来更新最终答案.更新答案后返回Vnow供父节点继续更新. 代码很简单. 有一个类似的很有趣的题目,给定一个二叉树,选择一条路径,使得权值最大的和最小的相差最大.参考POJ3728 cla…

版权声明:本文为博主原创文章.未经博主同意不得转载. https://blog.csdn.net/u011686226/article/details/32337735 题目来源:problem=1272" rel="nofollow">Light OJ 1272 Maximum Subset Sum 题意:选出一些数 他们的抑或之后的值最大 思路:每一个数为一个方程 高斯消元 从最高位求出上三角 消元前k个a[i]异或和都能有消元后的异或和组成 消元前 k 个 a[i…

Given a non-empty array containing only positive integers, find if the array can be partitioned into two subsets such that the sum of elements in both subsets is equal. Note: Both the array size and each of the array element will not exceed 100. Exam…

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…

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…

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. 解题思路: 最长路径和要分几种情况考虑,对于这样一个节点 cur / \ left right 设left是左子树的最长路径和,right是右子树的最长路径和,要求当前…

Given a non-empty array containing only positive integers, find if the array can be partitioned into two subsets such that the sum of elements in both subsets is equal. Note: Each of the array element will not exceed 100. The array size will not exce…

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 binary tree, find the maximum path sum from root. The path may end at any node in the tree and contain at least one node in it. 给一棵二叉树,找出从根节点出发的路径中,和最大的一条. 这条路径可以在任何二叉树中的节点结束,但是必须包含至少一个点(也就是根了). /** * Definition of TreeNode: * public class Tr…

Given a binary tree, find the maximum path sum. The path may start and end at any node in the tree. 找树的最大路径和 注意路径可以从任意点起始和结束. 我发现我真的还挺擅长树的题目的,递归不难.就是因为有个需要比较的量(最大和),所以需要再写一个函数. 因为路径可以从任意点起始和结束,所以每次递归的时候左右子树小于等于0的就可以不管了. #include <iostream> #include…

Given a binary tree, find the maximum path sum. The path may start and end at any node in the tree. Example Given the below binary tree: 1 / \ 2 3 return 6. For this problem we need to think about the problem in this way. Now we want the largest 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. 算法:(有点动态规划的思想)首先明确要自底向上进行计算,只考虑当前节点root,我们从子节点向上返回的是一条线路目前的最大值,该线路最高层(最上面)的节点是该子节点,并且该子节点…

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. 对于树,我们可以找到其左右子树中终止于根节点的最大路径值,称为最大半路径值,如果都是正数,则可以把它们以及根节点值相加,如果其中有负数,则舍弃那一边的值(即置为零).如此可以…

Problem Link: http://oj.leetcode.com/problems/binary-tree-maximum-path-sum/ For any path P in a binary tree, there must exists a node N in P such that N is the ancestor node of all other nodes in P. We call such N as the root of P, or P roots at N. T…

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 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…