解题思路:本题是一道图的题目,但是无向图,给定的输入是图的各个边,题目中给出一个关键信息(Each node has labels in the set {0, 1, ..., edges.length})可知图中没有环,如果是有环的图这个题是无解的.最好的证明方法就是反正法,如果有环的话标号最大的节点必然小于边的数量,例如[0, 1], [1, 2], [0, 2], 三个节点且三条边,但编号最大的节点小于边的数量. 题目的解法依然是在图上做dfs寻找答案,因为是无向图,对于一个节点来说,可以…

http://www.geeksforgeeks.org/diameter-of-a-binary-tree/ #include <iostream> #include <vector> #include <algorithm> #include <queue> #include <stack> using namespace std; struct node { int data; struct node *left, *right; node…

2019-11-03 21:37:59 一.Diameter of Binary Tree 问题描述: 问题求解: 解法一.第一反应是树上动归,每个节点保存一下左右的最大深度,最后以每个节点作为中枢计算最大的长度即可. public int diameterOfBinaryTree(TreeNode root) { Map<TreeNode, int[]> map = new HashMap<>(); dfs(root, map); int res = 0; for (TreeNo…

https://www.hackerrank.com/contests/hourrank-19/challenges 第一题略. 第二题是nim博弈,问删掉一个区间的石子,使得先手败的方案有几种,明显维护前缀异或,然后一直加方案数就好了 #include <cstdio> #include <cstring> #include <cmath> #include <queue> #include <vector> #include <time…

Forethought Future Cup - Elimination Round 窝也不知道这是个啥比赛QwQ A. Love "A" 给你一个串,你可以删去若干个元素,使得最后a的个数严格大于一半.求最大串长. #include<iostream> #include<cstdio> #include<cstring> using namespace std; char s[55];int v=0,n; int main() { scanf(&q…

1146C Tree Diameter 题意 交互题.有一棵 \(n(n\le 100)\) 个点的树,你可以进行不超过 \(9\) 次询问,每次询问两个点集中两个不在同一点集的点的最大距离.求树的直径. 题解 和 GXOI2019旅行者 基本类似,二进制分组,对于每一位,编号当前位为 \(0\) 的分到一组,当前位为 \(1\) 的分到另一组.最大询问次数为 \(\log 100 = 7\) code #include<cstdio> int v1[105],v2[105]; int mai…

https://leetcode.com/problems/diameter-of-binary-tree/#/description Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This…

Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longestpath between any two nodes in a tree. This path may or may not pass through the root. Example:Given a binary tr…

Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longestpath between any two nodes in a tree. This path may or may not pass through the root. Example:Given a binary tr…

Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root. Example:Given a binary t…