POJ3180 Strong Connectivity

Test instructions: Given a graph of n-point m edges, ask how many strongly connected component points are greater than or equal to 2.

Test instructions understand the basic there is no problem.

1#include <stdio.h>2#include <string.h>3#include <stack>4#include <queue>5 using namespacestd;6 7 Const intmaxn=1e4+5;8 Const intmaxm=5e4+5;9 Ten inthead[maxn],point[maxm],nxt[maxm],size; One intn,t,scccnt; A intSTX[MAXN],LOW[MAXN],SCC[MAXN]; - intNUM[MAXN]; -stack<int>S; the  - voidinit () { -memset (head,-1,sizeof(head)); -Size=0; +memset (NUM,0,sizeof(num)); - } +  A voidAddintAintb) { atpoint[size]=b; -nxt[size]=Head[a]; -head[a]=size++; - } -  - voidDfsints) { instx[s]=low[s]=++T; - S.push (S); to      for(intI=head[s];~i;i=Nxt[i]) { +         intj=Point[i]; -         if(!Stx[j]) { the Dfs (j); *low[s]=min (low[s],low[j]); $         }Panax Notoginseng         Else if(!Scc[j]) { -low[s]=min (low[s],stx[j]); the         } +     } A     if(low[s]==Stx[s]) { thescccnt++; +          while(1){ -             intu=S.top (); S.pop (); $scc[u]=scccnt; $num[scccnt]++; -             if(S==u) Break; -         } the     } - }Wuyi  the voidSETSCC () { -memset (STX,0,sizeof(STX)); Wumemset (SCC,0,sizeof(SCC)); -T=scccnt=0; About      for(intI=1; i<=n;++i)if(!Stx[i]) DFS (i); $ } -  - intMain () { -     intm; Ascanf"%d%d",&n,&m); + init (); the      while(m--){ -         intb; $scanf"%d%d",&a,&b); the Add (A, b); the     } the SETSCC (); the     intans=0; -      for(intI=1; i<=scccnt;++i)if(num[i]>1) ans++; inprintf"%d\n", ans); the     return 0; the}

View Code

POJ3180 Strong Connectivity