UVa506 - System Dependencies

来源：互联网发布：巨人网络借壳上市过程编辑：程序博客网时间：2024/05/16 12:21
#include<iostream>#include<string>#include<map>#include<sstream>#include<vector>#include<algorithm>using namespace std;const int maxn=10000;int cnt,status[maxn];string name[maxn];map<string,int>ids;vector<int> depend[maxn],depend2[maxn],installed;int get_id(string s){    if(ids.count(s)) return ids[s];    name[cnt]=s;    return ids[s]=cnt++;}bool needed(int item){    for(int i=0;i<depend2[item].size();++i)        if(status[depend2[item][i]]) return true;    return false;}void install(int item,bool toplevel){    if(!status[item]){        for(int i=0;i<depend[item].size();i++)            install(depend[item][i],false);        cout<<"   Installing "<<name[item]<<'\n';        status[item]=toplevel?1:2;        installed.push_back(item);    }}void remove(int item,bool toplevel){    if((toplevel||status[item]==2)&&!needed(item)){        status[item]=0;        installed.erase(remove(installed.begin(),installed.end(),item),installed.end());        cout<<"   Removing "<<name[item]<<'\n';        for(int i=0;i<depend[item].size();i++)            remove(depend[item][i],false);    }}int main(){    ios::sync_with_stdio(false);    string s,cmd;    while(getline(cin,s)){        cout<<s<<'\n';        if(s[0]=='E') break;        stringstream ss(s);        ss>>cmd;        if(cmd[0] == 'L'){            for(int i=0;i<installed.size();++i)                cout<<"   "<<name[installed[i]]<<'\n';            }else{                int id1,id2;                string s1,s2;                ss>>s1;                id1=get_id(s1);                if(cmd[0]=='D'){                    while(ss>>s2){                        id2=get_id(s2);                         depend[id1].push_back(id2);                        depend2[id2].push_back(id1);                    }                }                if(cmd[0]=='I')                {                    if(status[id1]) cout<<"   "<<s1<<" is already installed.\n";                        else install(id1,true);                }                if(cmd[0]=='R'){                    if(!status[id1]) cout<<"   "<<s1<<" is not installed.\n";                    else if(needed(id1)) cout<<"   "<<s1<<" is still needed.\n";                    else remove(id1,true);                }            }    }    return 0;}
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