天呢,好神奇的一个DP23333%%%%% 因为1.向左走1格的话相当于当前列和向左走列全选 2.想做走超过1的话可以有上下走替代.而且只能在相邻行向左. 全选的情况只能从第1行和第3行转移,相反全选的情况也只能转移到第1行和第3行. (大雾,DP太玄乎了,不是很懂2333) #include<bits/stdc++.h> #define LL long long #define N 100005 #define lowbit(x) x&(-x) using namespace std…

Codeforces 762D 题目大意: 给定一个\(3*n(n \leq 10^5)\)的矩形,从左上角出发到右下角,规定每个格子只能经过一遍.经过一个格子会获得格子中的权值.每个格子的权值\(a_{ij}\)满足\(-10^9 \leq a_{ij} \leq 10^9\).最大化收益 题解: 乍一看,好麻烦! 最主要的是因为他能够往回走. 但是我们画图可以发现:每次往回走一定不用超过1次. 也就是说,最多只能走成这样 而不会走成这样 因为下图的走法一定可以用上图组合,并且 由于只用3行的…

http://codeforces.com/problemset/problem/762/D 因为是3*n很巧妙的地方是 往左走两步或更多的走法都可以用往回走以一步 并走完一列来替换 那么走的方法就大大减少 左边一列转移到右边一列 每个 格子的转移方法枚举出来 用动态规划即可解决 最主要的是因为他能够往回走.但是我们画图可以发现:每次往回走一定不用超过1次.也就是说,最多只能走成这样 而不会走成这样 因为下图的走法一定可以用上图组合,并且由于只用3行的特性,每次向回走实际上是取走了所有的数.所以…

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…

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…

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 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…

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…