对于询问(x,y),恰经过一条非树边且不经过树上两点间路径的路径数为: ·若x与y成祖先-孩子关系,假设y是x的祖先,z是y到x方向的第一个节点,则 ans=起点在x的子树里,且终点不在z的子树里的非树边数 ·若x与y不成祖先-孩子关系,则 ans=起点在x的子树里,且终点在y的子树里的非树边数 由于不经过任何非树边也有一解,所以答案要加1 求出DFS序后线段树合并即可解决 #include<cstdio> const int N=100010,BUF=10500100; int n,m,i,…

[BZOJ3488][ONTAK2010]Highways Description 给一棵n个点的树以及m条额外的双向边q次询问,统计满足以下条件的u到v的路径:恰经过一条额外的边不经过树上u到v的路径上的边 Sample Input 9 1 2 2 3 4 2 1 5 5 6 7 5 7 8 9 7 4 2 5 3 4 6 4 8 3 4 4 9 2 5 1 6 1 7 Sample Output 1 4 2 2 题解:题意有点问题,不过你看英文就能知道,只走树边也算一条路径,所以答案先+1.…

题目描述 一棵n个点的树,给定m条路径,q次询问包含一条路径的给定路径的个数+1 输入 The first line of input contains a single integer N(1<=N<=100000) - the number of cities in Byteland. Cities are numbered from 1 to n . Each of the next N -1 lines contains two integers Ai, Bi(1<=Ai,Bi&…

Search GO 说明:输入题号直接进入相应题目,如需搜索含数字的题目,请在关键词前加单引号 Problem ID Title Source AC Submit Y 1000 A+B Problem 10983 18765 Y 1036 [ZJOI2008]树的统计Count 5293 13132 Y 1588 [HNOI2002]营业额统计 5056 13607 1001 [BeiJing2006]狼抓兔子 4526 18386 Y 2002 [Hnoi2010]Bounce 弹飞绵羊 43…

总时间限制: 1000ms 内存限制: 65536kB描述The island nation of Flatopia is perfectly flat. Unfortunately, Flatopia has no public highways. So the traffic is difficult in Flatopia. The Flatopian government is aware of this problem. They're planning to build some h…

Highways Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 23421   Accepted: 10826 Description The island nation of Flatopia is perfectly flat. Unfortunately, Flatopia has no public highways. So the traffic is difficult in Flatopia. The Fl…

Description The island nation of Flatopia is perfectly flat. Unfortunately, Flatopia has no public highways. So the traffic is difficult in Flatopia. The Flatopian government is aware of this problem. They're planning to build some highways so that i…

点击打开链接 Highways Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 19004   Accepted: 8815 Description The island nation of Flatopia is perfectly flat. Unfortunately, Flatopia has no public highways. So the traffic is difficult in Flatopia.…

题目连接 http://poj.org/problem?id=2485 Highways Description The island nation of Flatopia is perfectly flat. Unfortunately, Flatopia has no public highways. So the traffic is difficult in Flatopia. The Flatopian government is aware of this problem. They…

网络流/费用流 Orz太神犇了这题…… 我一开始想成跟Intervals那题一样了……每个数a[i]相当于覆盖了(a[i]-n,a[i]+n)这个区间……但是这样是错的!!随便就找出反例了……我居然还一直当正解…… 实际上刚刚那个思路还有一个问题:题目中的长度为N的区间指的是给的原序列!而不是权值的区间!题就理解错了…… 看了下zyf的题解,才明白过来,要用跟志愿者招募一样的方法来做:另外,志愿者招募时每种志愿者是有无限多名的,但这题中每个数只能选一次,所以边权为a[i]的边的流量不能是INF,…