题目大意 给定一棵树,要求你按给定的叶子节点顺序对整棵树进行遍历,并且恰好经过2*n-1个点,输出任意一条符合要求的路径 题解 每次从叶子节点开始遍历到上一个叶子节点就OK了, 这个就是符合要求的路径 代码: #include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #include <vector> using namespace std; #de…

D. Ant on the Tree time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Connected undirected graph without cycles is called a tree. Trees is a class of graphs which is interesting not only for…

POJ.3321 Apple Tree ( DFS序 线段树 单点更新 区间求和) 题意分析 卡卡屋前有一株苹果树,每年秋天,树上长了许多苹果.卡卡很喜欢苹果.树上有N个节点,卡卡给他们编号1到N,根的编号永远是1.每个节点上最多结一个苹果.卡卡想要了解某一个子树上一共结了多少苹果. 现在的问题是不断会有新的苹果长出来,卡卡也随时可能摘掉一个苹果吃掉.你能帮助卡卡吗? 前缀技能 边表存储树 DFS时间戳 线段树 首先利用边表将树存储下来,然后DFS打上时间戳.打上时间戳之后,我们就知道书上节点对…

题目链接:点击打开链接 题意: 给定n个节点的树 1为根 则此时叶子节点已经确定 最后一行给出叶子节点的顺序 目标: 遍历树并输出路径.要求遍历叶子节点时依照给定叶子节点的先后顺序訪问. 思路: 给每一个节点加一个优先级. 把最后一个叶子节点到父节点的路径上的点优先级改为1 把倒数第二个叶子节点到父节点的路径上的点优先级改为2 如此每一个点就有一个优先级,每一个訪问儿子节点时先訪问优先级大的就可以 对于无解的推断:得到的欧拉序列不满足输入的叶子节点顺序即是无解. #include <cstdio…

题目链接:http://codeforces.com/contest/620/problem/E E. New Year Tree time limit per test 3 seconds memory limit per test 256 megabytes input standard input output standard output The New Year holidays are over, but Resha doesn't want to throw away the N…

Apple Tree Time Limit: 2000MS   Memory Limit: 65536K       Description There is an apple tree outside of kaka's house. Every autumn, a lot of apples will grow in the tree. Kaka likes apple very much, so he has been carefully nurturing the big apple t…

Apple Tree Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 26762   Accepted: 7947 Description There is an apple tree outside of kaka's house. Every autumn, a lot of apples will grow in the tree. Kaka likes apple very much, so he has been…

B. Alyona and a tree 题目连接: http://codeforces.com/contest/739/problem/B Description Alyona has a tree with n vertices. The root of the tree is the vertex 1. In each vertex Alyona wrote an positive integer, in the vertex i she wrote ai. Moreover, the g…

题意:给出一棵树,共有n个节点,其中根节点是Kefa的家,叶子是restaurant,a[i]....a[n]表示i节点是否有猫,问:Kefa要去restaurant并且不能连续经过m个有猫的节点有多少条路径: 思路:先用vector数组建树: 再dfs..(第一次用vector建树,还看了别人的代码,果然是zz): 代码: #include <bits/stdc++.h> #define ll long long #define MAXN 100000+10 using namespace…

C. Valera and Elections   The city Valera lives in is going to hold elections to the city Parliament. The city has n districts and n - 1 bidirectional roads. We know that from any district there is a path along the roads to any other district. Let's…