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…

Codeforces Round #499 (Div. 1) F. Tree 题目链接 \(\rm CodeForces\):https://codeforces.com/contest/1010/problem/F Solution 设\(v_i\)表示第\(i\)个点的果子数,设\(b_i=v_i-\sum_{x\in son}v_x\),显然依题意要满足\(b_i\geqslant 0\). 根据差分的性质我们可以得到\(\sum b_i=x\). 假设我们硬点树上剩下了\(m\)个点,则…

C. Kefa and Park Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/580/problem/C Description Kefa decided to celebrate his first big salary by going to the restaurant. He lives by an unusual park. The park is a rooted tree con…

任意门:http://codeforces.com/contest/1118/problem/F1 F1. Tree Cutting (Easy Version) time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You are given an undirected tree of nn vertices. Some vert…

传送门:http://codeforces.com/contest/1092/problem/F F. Tree with Maximum Cost time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You are given a tree consisting exactly of nn vertices. Tree is a…

D. Tree Requests time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Roman planted a tree consisting of n vertices. Each vertex contains a lowercase English letter. Vertex 1 is the root of the…

C. Kefa and Park time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Kefa decided to celebrate his first big salary by going to the restaurant. He lives by an unusual park. The park is a roote…

题意: 给你n个节点,这n个节点构成了一颗以1为树根的树.每一个节点有一个初始值bi,从任意节点 i 的子树中选择任意k个节点,并按他的意愿随机排列这些节点中的数字,从而产生k⋅ai 的成本.对于一个节点i你需要将bi改成ci. 这个bi值和ci值的范围是[0,1] 题解: 对于一个节点,如果它的bi==ci,那么我们就不用管它(因为你改变它的值,那么肯定之后还要花费成本再改回来,增加了成本).那么我们首先找出来一共有多少个节点bi!=ci ,然后总权值肯定是 num1*a1+num2*a2..…

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…

https://codeforces.com/contest/1118/problem/F1 #include<bits/stdc++.h> using namespace std; int n; vector<int> color; vector<vector<int> > tree; ,blue=; ; pair<){ ); ); ;i<tree[v].size();i++){ int u=tree[v][i]; if(u!=p){//避免回…

C. Xor-tree Time Limit: 1 Sec  Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/430/problem/C Description Iahub is very proud of his recent discovery, propagating trees. Right now, he invented a new tree, called xor-tree. After this new revolu…

题目链接: http://codeforces.com/contest/675/problem/D 题意: 给你一系列点,叫你构造二叉搜索树,并且按输入顺序输出除根节点以外的所有节点的父亲. 题解: n有10^5,如果直接去建树,最会情况会O(n^2)t掉. 因此我们需要利用一些二叉搜索树的性质: 对于当前输入节点v,找出已经输入的最大的l和最小的r使得l<v<r. 由于输入v之前l和r中间是没有数的,所以l和r必定为祖先和后代的关系,如果不是的话,就会导致l和r中间还有数(l和r的公共祖先)…

题目链接:375D - Tree and Queries 题目大意:给你一个有n个点的树,每个点都有其对应的颜色,给出m次询问(v,k),问v的子树中有多少种颜色至少出现k次 题解:先对所有的询问进行分类,即对所有相同的v合并到一起,这样就能转为离线处理(更新每个点的状态时同时求出答案) 开两个map<int,int>,cnt[i][j]表示 i 节点的子树中 j 颜色出现了多少次,f[i][j]则表示 i 节点的子树中至少出现 j 次的颜色个数.dfs的时候暴力枚举所有颜色合并能够得出正确答…

A. Maze 题目连接: http://codeforces.com/contest/377/problem/A Description Pavel loves grid mazes. A grid maze is an n × m rectangle maze where each cell is either empty, or is a wall. You can go from one cell to another only if both cells are empty and h…

D. Tree Construction 题目连接: http://www.codeforces.com/contest/675/problem/D Description During the programming classes Vasya was assigned a difficult problem. However, he doesn't know how to code and was unable to find the solution in the Internet, so…

题意与分析(CodeForces 580C) 给你一棵树,然后每个叶子节点会有一家餐馆:你讨厌猫(waht?怎么会有人讨厌猫),就不会走有连续超过m个节点有猫的路.然后问你最多去几家饭店. 这题我写的挫的要死,实际上只需要一次dfs就可以解决了,我愣是用了一次bfs+一次dfs来写--dfs是为了判断是否是叶子节点的....但是bfs干的活完全可以让dfs在找叶子节点的时候顺带解决了,所以就很坑. 一个比较好的写法见https://www.cnblogs.com/qscqesze/p/48315…

题目大意 给出一棵树,边上有权值,要求给出一个1到n的排列p,使得sigma d(i, pi)最大,且p的字典序尽量小. d(u, v)为树上两点u和v的距离 题解:一开始没看出来p需要每个数都不同,直接敲了个轻重边剖分orz,交上去才发现不对 #include <iostream> #include <cstdio> #include <cstring> #include <vector> #define fi first #define se secon…

D. MADMAX time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output As we all know, Max is the best video game player among her friends. Her friends were so jealous of hers, that they created an actu…

题目链接:http://codeforces.com/contest/767/problem/C 题解:类似于提着一串葡萄,用剪刀剪两条藤,葡萄分成了三串.问怎样剪才能使三串葡萄的质量相等. 首先要做的就是统计葡萄的总质量tot.之后就是找到两子串质量为(tot/3)的葡萄(如果除不尽,则必定找不到),那么剩下的就是dfs搜索了. 我一开始的做法是先建一棵记录子树质量和的树,然后再从上往下dfs,如果找到了,就把它剪掉.后来发现被剪掉的那一串可能就含有两串质量为(tot/3)的葡萄(这里质量 可…

终于补好了. 题目链接: http://codeforces.com/contest/580/problem/E E. Kefa and Watch time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output One day Kefa the parrot was walking down the street as he was on t…

580A. Kefa and First Steps 题目链接: A. Kefa and First Steps 题意描述: 给出一个序列,求最长不降连续子序列多长? 解题思路: 水题,签到 代码: #include <cstdio> #include <cstring> #include <iostream> #include <algorithm> using namespace std; int main () { int e, s, num, n,…

题目链接:https://codeforces.com/contest/1363/problem/E 题意 有一棵 $n$ 个结点,根为结点 $1$ 的树,每个结点有一个选取代价 $a_i$,当前 $b_i$,目标数字 $c_i$ .每次可以选择以一个结点为根节点的子树中的 $k$ 个结点交换它们的 $b_i$,总代价为 $k \times a_{root}$ ,判断能否把所有结点都变为目标数字以及最小代价. 题解 因为每棵子树都可以被包含进更大的子树中,所以对于每棵子树的根节点,它的最小选取代…

Tree Construction Problem's Link ---------------------------------------------------------------------------- Mean: 给定n个数,按照构造Binary Search Tree的方式来构造BST树,按顺序输出每一个非root结点的父节点的值. analyse: 构造BST树最坏情况下时间复杂度为O(n),肯定会超时. 注意到只需要输出结点的父节点的值,不需要真的构造BST树. 插到第i…

题目链接:http://codeforces.com/problemset/problem/675/D 给你一个如题的二叉树,让你求出每个节点的父节点是多少. 用set来存储每个数,遍历到a[i]的时候查找比a[i]大的数的位置,然后插入,而父亲就是刚好比a[i]小的数或刚好大的数. 然后讨论是哪一个数. 比如给你3 1 2 ,如图 1的父亲是3 ,2的父亲是1. 那我其实只要找左边或右边出现最晚的数就行了,用pair的first表示a[i],second表示出现的顺序i. #include <…

E. Kefa and Watch Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/580/problem/E Description One day Kefa the parrot was walking down the street as he was on the way home from the restaurant when he saw something glittering b…

B. Kefa and Company Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/580/problem/B Description Kefa wants to celebrate his first big salary by going to restaurant. However, he needs company. Kefa has n friends, each friend wi…

A. Kefa and First Steps Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/580/problem/A Description Kefa decided to make some money doing business on the Internet for exactly n days. He knows that on the i-th day (1 ≤ i ≤ n) h…

D. Fedor and Essay time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output After you had helped Fedor to find friends in the «Call of Soldiers 3» game, he stopped studying completely. Today, the E…

题目链接:http://www.codeforces.com/problemset/problem/580/A题意:求最长连续非降子序列的长度.C++代码: #include <iostream> using namespace std; ; int n, a[maxn], tmp, ans; int main() { cin >> n; ; i < n; i ++) cin >> a[i]; tmp = ans = ; ; i <= n; i++) ])…

http://codeforces.com/contest/580/problem/D 题意: 有个人去餐厅吃饭,现在有n个菜,但是他只需要m个菜,每个菜只吃一份,每份菜都有一个欢乐值.除此之外,还有一些规则,x,y,w代表的是如果x吃完后吃y,那么还能获得额外的w欢乐值.计算所能获得的最大欢乐值. 思路: 看到别人说要用状压dp来做,我才恍然大悟啊,感觉自己对于状压dp实在是太不敏感了. d[i][j]表示在当前i状态时最后一份吃的是j的最大欢乐值. 状态转移什么的请看代码吧. #includ…