poj3687拓撲排序

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反向建圖

#include <cstdio>#include <cstring>#include <algorithm>#include <climits>#include <string>#include <iostream>#include <map>#include <cstdlib>#include <list>#include <set>#include <queue>#include <stack>using namespace std;const int INF=0xfffffff;int main(){    int n,m,Icase;    int vis[300];    int G[300][300];    int in[300];    int topo[300];    while(cin>>Icase){        while(Icase--){            memset(topo,0,sizeof(topo));            memset(G,0,sizeof(G));            memset(vis,0,sizeof(vis));            memset(in,0,sizeof(in));            cin>>n>>m;            for(int i=0;i<m;i++){                int a,b;                cin>>a>>b;                if(!G[a][b]){                    in[a]++;                    G[a][b]=1;                }            }            int flag=1;            for(int i=n;i>=1;i--){                int sign;                bool t=false;                for(int j=1;j<=n;j++){                    if(in[j]==0&&!vis[j]){                        sign=j; t=true;                    }                }                if(!t){                    flag=0;break;                }              //  vis[sign]=1;                topo[i]=sign;              //  cout<<topo[i]<<endl;system("pause");                for(int j=1;j<=n;j++){                    if(!vis[j]&&G[j][sign]){                        in[j]--;                    }                }                vis[sign]=1;            }            if(!flag)cout<<-1<<endl;            else{                int a[300];                for(int i=1;i<=n;i++){                    a[topo[i]]=i;                }                for(int i=1;i<=n;i++){                    if(i==1) cout<<a[i];                    else cout<<" "<<a[i];                }                cout<<endl;            }        }    }    return 0;}