SDUT OJ 2140 图结构练习——判断给定图是否存在合法拓扑序列

#include<iostream>#include<memory.h>using namespace std;int tp[11][11],visit[11];int main(){    int n,m,i,j,k,s,o,c;int flag,count,a,b;while(cin>>n>>m){s=1;o=0;count=0;memset(tp,0,sizeof(tp));memset(visit,0,sizeof(visit));for(i=1;i<=m;i++){cin>>a>>b;tp[a][b]=1;}/*for(i=1;i<=n;i++){for(j=1;j<=n;j++)if(j==n)cout<<tp[i][j]<<endl;elsecout<<tp[i][j]<<" ";}*/while(s){flag=0;c=0;o++;for(j=1;j<=n;j++){for(i=1;i<=n;i++){if(tp[i][j]==0 && visit[j]==0){                        c++;}else{break;}  }if(c==n){flag=0;c=0;}else{flag=1;c=0;}if(flag==0){for(k=1;k<=n;k++)tp[j][k]=0;count++;visit[j]=1;}}if(o>n)s=0;elses=1;}/*for(i=1;i<=n;i++){for(j=1;j<=n;j++)if(j==n)cout<<tp[i][j]<<endl;elsecout<<tp[i][j]<<" ";}*/if(count==n)cout<<"YES"<<endl;else cout<<"NO"<<endl;}return 0;}/*#include<iostream>#include<memory.h>using namespace std;int tp[11][11],visit[11];int n,m,u,v;int dfs(int u){visit[u]=-1;for(v=1;v<=n;v++){if(tp[u][v]==1){if(visit[v]<0)return 0;else if(!visit[v] && !dfs(v))return 0;}}visit[u]=1;return 1;}int topu(){for(u=1;u<=n;u++){if(!visit[u]){if(!dfs(u))return 0;}}return 1;}int main(){int i;while(cin>>n>>m){memset(tp,0,sizeof(tp));memset(visit,0,sizeof(visit));    for(i=0;i<m;i++){cin>>u>>v;tp[u][v]=1;}    int k=topu();if(k==0)cout<<"NO"<<endl;elsecout<<"YES"<<endl;}return 0;}*/