UVa 11060 Beverages

#include <bits/stdc++.h>
using namespace std;

int n,m;
vector<string> bev;   //store all bevarages with order input
map<string,int> indegree;
map<string,vector<string> > adjList;


int main()
{
    int c =0;
    while(cin>>n){
        bev.clear();
        indegree.clear();
        adjList.clear();

        string str;
        for(int i=0;i<n;i++){
            cin>>str;
            bev.push_back(str);
        }
        cin>>m;
        string str1;
        for(int i=0;i<m;i++){
            cin>>str>>str1;
            indegree[str1]++;
            adjList[str].push_back(str1);
        }

        queue<string> q;
        int i=0;
        while(indegree[bev[i]]>0){i++;}
        q.push(bev[i]);
        vector<string> u1=adjList[bev[i]];
        for(int j=0;j<u1.size();j++){
            indegree[u1[j]]--;
        }
        bev.erase(bev.begin()+i);
        vector<string> tp;

        while(!q.empty()){
            string p=q.front();
            q.pop();
            tp.push_back(p);
            int i=0;
            while(indegree[bev[i]] && i<bev.size()){i++;}
            if(i==bev.size()) break;
            q.push(bev[i]);  //push into queue cái có indegree=0
            vector<string> u=adjList[bev[i]];
            for(int j=0;j<u.size();j++){
                --indegree[u[j]]; //descrease all nodes connect with node pushed
            }

            bev.erase(bev.begin()+i);   //erase node from input
        }
        cout<<"Case #"<<++c<<": Dilbert should drink beverages in this order:";
        for(int j=0;j<tp.size();j++){
            cout<<" "<<tp[j];
        }
        cout<<"."<<endl;
        cout<<endl;

    }
    return 0;
}
//hieudoanitus