hdu1269 Strong Connectivity

Test instructions: Determines whether all points in a given direction graph can reach each other.

is to ask if there is only one strong connected component.

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=1e5+5;9 Ten inthead[maxn],point[maxm],nxt[maxm],size; One intn,t,scccnt; A intSTX[MAXN],LOW[MAXN],SCC[MAXN]; -stack<int>S; -  the voidinit () { -memset (head,-1,sizeof(head)); -Size=0; - } +  - voidAddintAintb) { +point[size]=b; Anxt[size]=Head[a]; athead[a]=size++; - } -  - voidDfsints) { -stx[s]=low[s]=++T; - S.push (S); in      for(intI=head[s];~i;i=Nxt[i]) { -         intj=Point[i]; to         if(!Stx[j]) { + Dfs (j); -low[s]=min (low[s],low[j]); the         } *         Else if(!Scc[j]) { $low[s]=min (low[s],stx[j]);Panax Notoginseng         } -     } the     if(low[s]==Stx[s]) { +scccnt++; A          while(1){ the             intu=S.top (); S.pop (); +scc[u]=scccnt; -             if(S==u) Break; $         } $     } - } -  the voidSETSCC () { -memset (STX,0,sizeof(STX));Wuyimemset (SCC,0,sizeof(SCC)); theT=scccnt=0; -      for(intI=1; i<=n;++i)if(!Stx[i]) DFS (i); Wu } -  About intMain () { $     intm; -      while(SCANF ("%d%d", &n,&m)!=eof&&n+m) { - init (); -          while(m--){ A             intb; +scanf"%d%d",&a,&b); the Add (A, b); -         } $ SETSCC (); the         if(scccnt==1) printf ("yes\n"); the         Elseprintf"no\n"); the     } the     return 0; -}

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hdu1269 Strong Connectivity