Source Code

• Source Code

  #include"iostream"
  #include"stack"
  #include"vector"
  #include"cstdio"
  using namespace std;
  vector< vector<int> > G;//採用鄰接表儲存圖
  vector<int> degree;     //度數表
  vector<int> is_in_stack;//判斷是否入過棧
  vector<int
   
  > ans;        //儲存答案
  int n,m;                //點數 弧數
  int topo_sort(){
      stack<int> st;
      for(int i=1;i<=n;i++){  //先找到入度為0的點 壓入棧中
          if(degree[i]==0){
              st.push(i);
              is_in_stack[i] = 1; //更新點的標誌
          }
      }
      while(!st.empty()){
          int now = st.top();st.pop
   
  ();
          ans.push_back(now);
          for(int i=0;i<G[now].size();i++){//把鄰接的點的度數更新
              degree[G[now][i]]--;
          }
          for(int i=1;i<=n;i++){
              if(degree[i]==0&&!is_in_stack[i]){//把更新之後的圖中入度為0的點入棧
                  st.push(i);
                  is_in_stack[i]=1;
              }
   
  
          }
      }
  }
  int main(){
      while(cin>>n){
          G.resize(n+1);
          is_in_stack.resize(n+1);
          degree.resize(n+1);
          for(int i=1;i<=n;i++){
              int ed;
              while(scanf("%d",&ed)&&ed){
                  G[i].push_back(ed);
              }
          }
          for(int i=1;i<=n;i++){
              is_in_stack[i]=0;
              for(int j=0;j<G[i].size();j++){
                  degree[G[i][j]]++;
              }
          }
          topo_sort();
          int first = 1;
          for(int i=0;i<ans.size();i++){
              if(first) {first = 0;cout<<ans[i];}
              //else cout<<"--->"<<ans[i];
              else cout<<" "<<ans[i];
          }
          cout<<endl;
      }
      return 0;
  
  }