bzoj1654 [Usaco2006 Jan]The Cow Prom 奶牛舞会
Description
The N (2 <= N <= 10,000) cows are so excited: it's prom night! They are dressed in their finest gowns, complete with corsages and new shoes. They know that tonight they will each try to perform the Round Dance. Only cows can perform the Round Dance which requires a set of ropes and a circular stock tank. To begin, the cows line up around a circular stock tank and number themselves in clockwise order consecutively from 1..N. Each cow faces the tank so she can see the other dancers. They then acquire a total of M (2 <= M <= 50,000) ropes all of which are distributed to the cows who hold them in their hooves. Each cow hopes to be given one or more ropes to hold in both her left and right hooves; some cows might be disappointed. For the Round Dance to succeed for any given cow (say, Bessie), the ropes that she holds must be configured just right. To know if Bessie's dance is successful, one must examine the set of cows holding the other ends of her ropes (if she has any), along with the cows holding the other ends of any ropes they hold, etc. When Bessie dances clockwise around the tank, she must instantly pull all the other cows in her group around clockwise, too. Likewise, if she dances the other way, she must instantly pull the entire group counterclockwise (anti-clockwise in British English). Of course, if the ropes are not properly distributed then a set of cows might not form a proper dance group and thus can not succeed at the Round Dance. One way this happens is when only one rope connects two cows. One cow could pull the other in one direction, but could not pull the other direction (since pushing ropes is well-known to be fruitless). Note that the cows must Dance in lock-step: a dangling cow (perhaps with just one rope) that is eventually pulled along disqualifies a group from properly performing the Round Dance since she is not immediately pulled into lockstep with the rest. Given the ropes and their distribution to cows, how many groups of cows can properly perform the Round Dance? Note that a set of ropes and cows might wrap many times around the stock tank.
Input
* Line 1: Two space-separated integers: N and M
* Lines 2..M+1: Each line contains two space-separated integers A and B that describe a rope from cow A to cow B in the clockwise direction.
Output
* Line 1: A single line with a single integer that is the number of groups successfully dancing the Round Dance.
Sample Input
2 4
3 5
1 2
4 1
INPUT DETAILS:
ASCII art for Round Dancing is challenging. Nevertheless, here is a
representation of the cows around the stock tank:
_1___
/**** \
5 /****** 2
/ /**TANK**|
\ \********/
\ \******/ 3
\ 4____/ /
\_______/
Sample Output
HINT
1,2,4这三只奶牛同属一个成功跳了圆舞的组合.而3,5两只奶牛没有跳成功的圆舞
我又在刷水了……这几天好颓啊
题意就是缩点之后统计包含2个以上点的强连通分量的个数
这题可以当模板吧……
#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
#include<queue>
#include<deque>
#include<set>
#include<map>
#include<ctime>
#define LL long long
#define inf 0x7ffffff
#define pa pair<int,int>
#define pi 3.1415926535897932384626433832795028841971
#define N 10010
#define M 50010
using namespace std;
int n,m,cnt;
struct edge{
int to,next;
}e[M];
int head[N];
inline void ins(int u,int v)
{
e[++cnt].to=v;
e[cnt].next=head[u];
head[u]=cnt;
}
int cnt2,cnt3;
int dfn[N],low[N];
int belong[N],size[N];
int zhan[N],top;bool inset[N];
inline void dfs(int x)
{
zhan[++top]=x;inset[x]=1;
low[x]=dfn[x]=++cnt2;
for (int i=head[x];i;i=e[i].next)
{
if(!dfn[e[i].to])
{
dfs(e[i].to);
low[x]=min(low[x],low[e[i].to]);
}else if(inset[e[i].to])
low[x]=min(low[x],dfn[e[i].to]);
}
if (dfn[x]==low[x])
{
cnt3++;
int p=-1;
while (p!=x)
{
p=zhan[top--];
inset[p]=0;
belong[p]=cnt3;
size[cnt3]++;
}
}
}
inline void tarjan()
{
for (int i=1;i<=n;i++)
if (!dfn[i])dfs(i);
}
inline LL read()
{
LL x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x*f;
}
int main()
{
n=read();m=read();
for (int i=1;i<=m;i++)
{
int x=read(),y=read();
ins(y,x);
}
tarjan();
int tot=0;
for(int i=1;i<=cnt3;i++)
tot+=(size[i]>1);
printf("%d\n",tot);
return 0;
}
bzoj1654 [Usaco2006 Jan]The Cow Prom 奶牛舞会的更多相关文章
- 【强连通分量】Bzoj1654 [Usaco2006 Jan]The Cow Prom 奶牛舞会
Description 约翰的N(2≤N≤10000)只奶牛非常兴奋,因为这是舞会之夜!她们穿上礼服和新鞋子,别上鲜花,她们要表演圆舞. 只有奶牛才能表演这种圆舞.圆舞需要一些绳索和一个圆形的 ...
- bzoj 1654: [Usaco2006 Jan]The Cow Prom 奶牛舞会 -- Tarjan
1654: [Usaco2006 Jan]The Cow Prom 奶牛舞会 Time Limit: 5 Sec Memory Limit: 64 MB Description The N (2 & ...
- 【BZOJ1654】[Usaco2006 Jan]The Cow Prom 奶牛舞会 赤果果的tarjan
Description The N (2 <= N <= 10,000) cows are so excited: it's prom night! They are dressed in ...
- bzoj:1654 [Usaco2006 Jan]The Cow Prom 奶牛舞会
Description The N (2 <= N <= 10,000) cows are so excited: it's prom night! They are dressed in ...
- 【BZOJ】1654: [Usaco2006 Jan]The Cow Prom 奶牛舞会(tarjan)
http://www.lydsy.com/JudgeOnline/problem.php?id=1654 请不要被这句话误导..“ 如果两只成功跳圆舞的奶牛有绳索相连,那她们可以同属一个组合.” 这句 ...
- P1654: [Usaco2006 Jan]The Cow Prom 奶牛舞会
裸的强连通 ; type node=record f,t:longint; end; var n,m,dgr,i,u,v,num,ans:longint; bfsdgr,low,head,f:arra ...
- bzoj 1654: [Usaco2006 Jan]The Cow Prom 奶牛舞会【tarjan】
几乎是板子,求有几个size>1的scc 直接tarjan即可 #include<iostream> #include<cstdio> #include<cstri ...
- 【BZOJ1720】[Usaco2006 Jan]Corral the Cows 奶牛围栏 双指针法
[BZOJ1720][Usaco2006 Jan]Corral the Cows 奶牛围栏 Description Farmer John wishes to build a corral for h ...
- BZOJ——1720: [Usaco2006 Jan]Corral the Cows 奶牛围栏
http://www.lydsy.com/JudgeOnline/problem.php?id=1720 Time Limit: 5 Sec Memory Limit: 64 MBSubmit: 1 ...
随机推荐
- spring 4 泛型注入
最近对系统进行改造,发现在泛型实例初始化的时候,得不到想要的泛型.或者需要强制转换. spring 4 开始支持泛型对象初始化,初始化方法如下: 注:使用配置文件的方法暂时还没有发现,下面是使用jav ...
- 【转】GCC4.6编译的warning -Werror
原文网址:http://blog.sina.com.cn/s/blog_605f5b4f0101bct7.html New warnings for unused variables and para ...
- PhpForm表单相关的超全局变量操作
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/ ...
- 安全:加固你的ssh 登录
SSH 是我们控制虚拟主机的一种途径,这个途径可以让我们拥有完全的控制权,如果对于这个控制权没有进行很好的安全处理,那么将会造成很大的安全问题. 我们可以在系统的日志文件 (例如:/var/ ...
- redis知识
http://www.cnblogs.com/moon521/p/5301895.html 菜鸟教程:http://www.runoob.com/redis/redis-tutorial.html
- functools:管理函数工具(部分)
# -*- coding: utf-8 -*- # python:2.x __author__ = 'Administrator' #functools:管理函数工具 #作用:处理其他函数的函数 #版 ...
- 用dTree组件生成无限级导航树
在做管理系统时不可避免要用到导航树,这种东西只要一次做好,就可以随处运行,目前比较好的组件是dTree,原则上可以达到无限级,当然实际运行中4,5级就已经很多了,dTree的速度还是不错的,而且是J ...
- Redis + Jedis + Spring 实例(对象的操作)
目录(?)[+] 不得不说,用哈希操作来存对象,有点自讨苦吃! 不过,既然吃了苦,也做个记录,也许以后API升级后,能好用些呢?! 或许,是我的理解不对,没有真正的理解哈希表. 一.预期 接上 ...
- 设计模式13---设计模式之观察者模式(Observer)(行为型)
1.场景模式抽象 订阅报纸的过程,如果报纸来了的时间不确定,那么订报纸的人如何知道呢?可以抽象为:当一个对象的状态发生改变的时候,如何让依赖他的所有对象得到通知,并进行相应的处理呢?生活中最常见的例子 ...
- poj1330Nearest Common Ancestors(LCA小结)
题目请戳这里 题目大意:意如其名. 题目分析:本题只有一个查询,所以可以各种乱搞过去. 不过对于菜鸟而言,还是老老实实练习一下LCA算法. LCA有很多经典的算法.按工作方式分在线和离线2种. tar ...