E. Famil Door and Roads 题目连接: http://www.codeforces.com/contest/629/problem/E Description Famil Door's City map looks like a tree (undirected connected acyclic graph) so other people call it Treeland. There are n intersections in the city connected b…

题目链接: http://www.codeforces.com/contest/629/problem/E 题解: 树形dp. siz[x]为x这颗子树的节点个数(包括x自己) dep[x]表示x这个节点的深度,从1开始(其实从什么开始都可以,我们这里用到的只是相对距离) 对于查询u,v,总共有三种情况: 1.u为公共祖先 设x为(u,v)链上u的儿子,则我们知道新边只能从非x子树的点(n-siz[x]连到以v为根的子树上的点(siz[v]) 则新边的总条数为(n-siz[x])*siz[v]…

Famil Door's City map looks like a tree (undirected connected acyclic graph) so other people call it Treeland. There are n intersections in the city connected by n - 1 bidirectional roads. There are m friends of Famil Door living in the city. The i-t…

C. Famil Door and Brackets 题目连接: http://www.codeforces.com/contest/629/problem/C Description As Famil Door's birthday is coming, some of his friends (like Gabi) decided to buy a present for him. His friends are going to buy a string consisted of roun…

题目链接: http://codeforces.com/contest/629/problem/C 题意: 长度为n的括号,已经知道的部分的长度为m,现在其前面和后面补充‘(',或')',使得其长度为n,且每个左括号都能找到右括号与它匹配. 题解: dp[i][j]表示长度为i,平衡度为j的合法括号序列的总数,这里平衡度定义是‘('比')'多多少个,或')'比’('多多少个. #include<iostream> #include<cstring> #include<cstd…

题意:做蛋糕,给出N个半径,和高的圆柱,要求后面的体积比前面大的可以堆在前一个的上面,求最大的体积和. 思路:首先离散化蛋糕体积,以蛋糕数量建树建树,每个节点维护最大值,也就是假如节点i放在最上层情况下的体积最大值dp[i].每次查询比蛋糕i小且最大体积的蛋糕,然后更新线段树.注意此题查询的技巧!!查询区间不变l,r,才能保证每次查到的是小且最大体积. #include<iostream> #include<string> #include<algorithm> #in…

题目链接 题意:给你一个有根树,假设有k个叶子节点,你可以给每个叶子节点编个号,要求编号不重复且在1-k以内.然后根据节点的max,minmax,minmax,min信息更新节点的值,要求根节点的值最大. 解法:考虑树形dp,若当前节点是nownownow,我们可以假设编号最大的一些数分布在当前节点的子节点中,显然,若当前节点为叶子节点,那么这个这个编号就是最大的.然后往上回溯,假设当前节点取得是maxmaxmax,那么就从子节点中取最大的数为当前节点的答案,如果取得是minminmin的话,就…

居然补完了 组合 A - Far Relative’s Birthday Cake import java.util.*; import java.io.*; public class Main { public static void main(String[] args) { Scanner cin = new Scanner (new BufferedInputStream (System.in)); int n = cin.nextInt (); int[] col = new int[…

B. Far Relative's Problem 题目连接: http://www.codeforces.com/contest/629/problem/B Description Famil Door wants to celebrate his birthday with his friends from Far Far Away. He has n friends and each of them can come to the party in a specific range of…

B. Far Relative’s Problem time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Famil Door wants to celebrate his birthday with his friends from Far Far Away. He has n friends and each of them c…