hdu-4857-Escape-Reverse topology sort + Priority queue

HDU-4857

Test instructions is to do a qualifying sort, using the topological sequence.

I started with a lot of WA, only to find that there are a few examples too, found 1->2->3 ... the order is not guaranteed.

Later I wanted to use and check the strong company, or WA;

Later found that the use of reverse topology sorting + priority queue to pass;

Notice here that the entry to the 0 is changed into a 0-degree queue

Here is the AC code:

#include <cstring>#include<queue>#include<cstdio>using namespaceStd;vector<int>to[30000+Ten];intn,m,cnt;intoutdeed[30000+Ten],topo [30000+Ten];voidinit () {memset (outdeed,0,sizeof(outdeed));  for(intI=1; i<=n;i++) to[i].clear (); memset (topo,0,sizeof(topo));}voidToposort () {priority_queue<int>Q;  for(intI=1; i<=n;i++)        if(!Outdeed[i]) Q.push (i); CNT=0;  while(!Q.empty ()) {        intTMP =Q.top ();        Q.pop (); topo[++cnt]=tmp; intK =to[tmp].size ();  for(intI=0; i<k;i++)        {            inttt =To[tmp][i]; OUTDEED[TT]--; if(outdeed[tt]==0) Q.push (TT); }    }}voidoutput () { for(inti=n;i>=1; i--) printf ("%d%c", topo[i],i==1?'\ n':' ');}intMain () {intT; scanf ("%d",&T);  while(t--) {scanf ("%d%d",&n,&m);        Init ();  for(intI=1; i<=m;i++)        {            intu,v; scanf ("%d%d",&u,&v);            To[v].push_back (U); Outdeed[u]++;        } toposort ();    Output (); }    return 0;}

hdu-4857-Escape-Reverse topology sort + Priority queue