"bzoj1051" [HAOI2006] Popular cattle Tarjan point of calculation points

"bzoj1051" [HAOI2006] Popular CattleJanuary 8, 2014 7450 Description

The desire of every cow is to become one of the most popular cows. Now there are n cows, give you m-pairs of integers (a, a, b), indicating that cow A is considered to be popular. This relationship is transitive, and if a thinks B is popular, B thinks C is popular, then bull a also thinks that Ox C is popular. Your task is to find out how many cows are considered popular by all cows.

Input

The first line is two numbers n,m. Next m line, two numbers per line, A, B, meaning that A is considered to be welcome (the information given may be repeated, that is, there may be multiple A, b)

Output

A number, that is, how many cows are considered popular by all cows.

Sample INPUT3 3
1 2
2 1
2 3Sample Output1 "data range"
10% of data n<=20, m<=50
30% of Data n<=1000,m<=20000
70% of Data n<=5000,m<=50000
100% of data n<=10000,m<=50000 code

#include <cstdio>#include<cmath>#include<cstring>#include<ctime>#include<iostream>#include<algorithm>#include<Set>#include<vector>#include<queue>#include<typeinfo>#include<map>#include<bits/stdc++.h>typedefLong Longll;using namespacestd;#defineINF 10000000inline ll read () {ll x=0, f=1; CharCh=GetChar ();  while(ch<'0'|| Ch>'9')    {        if(ch=='-') f=-1; CH=GetChar (); }     while(ch>='0'&&ch<='9') {x=x*Ten+ch-'0'; CH=GetChar (); }    returnx*F;}//***************************************************************inthead[10001],dfn[10001];structss{intTo,next; intHea;} e[10001*5];intt=1;intbcnt;intCNT;intbelong[10001];inthav[10001];int  out[10001];intn,m,top,low[10001],stacks[10001];intvis[10001];intinstack[10001];voidAddintUintv) {E[t].hea=u; E[t].to=v; E[t].next=Head[u]; Head[u]=t++;}voidDfsintu) {Dfn[u]=low[u]=++CNT; stacks[++top]=u; Instack[u]=1; Vis[u]=1;  for(intI=head[u];i;i=E[i].next) {        if(!Vis[e[i].to])            {DFS (e[i].to); Low[u]=min (low[u],low[e[i].to]); }        Else if(Instack[u]) {low[u]=min (low[u],dfn[e[i].to]);} }    intv=-1; if(low[u]==Dfn[u]) {bcnt++;  while(u!=v) {v=stacks[top--]; INSTACK[V]=0; BELONG[V]=CNT; HAV[BCNT]++; //vis[v]=0;        }    }}voidrebuild () { for(intI=1; i<=m;i++){        if(belong[e[i].hea]!=belong[e[i].to]) out[belong[e[i].hea]]++; }}voidTarjan () { for(intI=1; i<=n;i++){        if(!Vis[i]) DFS (i); } rebuild ();}voidWork () {intres=0, ans; //cout<<bcnt<<endl;     for(intI=1; i<=bcnt;i++){        if( out[i]==0) {res++; Ans=i; }       ///printf ("%d\n", Hav[i]);    }    if(res==1) {printf ("%d\n", Hav[ans]); }    Elseprintf"0\n");}intMain () {scanf ("%d%d",&n,&m); intb;  for(intI=1; i<=m; i++) {scanf ("%d%d",&a,&b);    Add (A, b);    } Tarjan ();    Work (); return 0;}

"bzoj1051" [HAOI2006] Popular cattle Tarjan point of calculation points