【例题 6-21 UVA - 506】System Dependencies

【链接】 我是链接,点我呀:)

【题意】

在这里输入题意

【题解】

记录每个物品它的依赖有哪些,以及它被哪些东西依赖就可以了。
显式安装的东西不能被隐式删除删掉(就是remove item,然后删除item的依赖的过程叫隐式删除,而删除item本身叫显式删除);
而只能被显式删除。
隐式安装的依赖则可以被显式或隐式删除都行。
(显示安装指的是 install item,安装item本身,而安装item的依赖,都称为是隐式的安装)

写个安装和删除的递归函数就好。

样例的答案有误。

remove browser那里应该是先remove tcpip 后remove html.

【代码】

/*
  	1.Shoud it use long long ?
  	2.Have you ever test several sample(at least therr) yourself?
  	3.Can you promise that the solution is right? At least,the main ideal
  	4.use the puts("") or putchar() or printf and such things?
  	5.init the used array or any value?
  	6.use error MAX_VALUE?
*/
#include <bits/stdc++.h>
using namespace std;

string s;
map <int,vector <int> > yilai,beiyilai;
map <int,int> status;
map <string,int> dic;
map <int,string> dic2;
vector <int> installed;
string ope;
int tot = 0;

void pd(string temp){
 	if (dic[temp]==0) {
 		dic[temp] = ++tot;
 		dic2[tot] = temp;
 	}
}

void ins(int id,bool highest){
	if (status[id]==0){
		if (yilai.find(id)!=yilai.end()){
			vector <int> v = yilai[id];
			int len = v.size();
			for (int i = 0;i < len;i++){
				int x = v[i];
				ins(x,0);
		 	}
	 	}
	 	cout << "   Installing "<<dic2[id] << endl;
	 	installed.push_back(id);
	 	status[id] = (highest?1:2);
	}
}

bool need(int x){
 	if (beiyilai.find(x)!=beiyilai.end()){
 	 	vector <int> v = beiyilai[x];
 	 	int len = v.size();
 	 	for (int i = 0;i < len;i++){
 	 	 	int x = v[i];
 	 	 	if (status[x]) return true;
 	 	}
 	}
 	return false;
}

void dele(int id,bool highest){
 	if ( !need(id) && (highest || status[id]==2)){
 		status[id] = 0;
 		cout << "   Removing " << dic2[id] << endl;
 		installed.erase(remove(installed.begin(),installed.end(),id),installed.end());
 		if (yilai.find(id)!=yilai.end()){
			vector <int> v = yilai[id];
			int len = v.size();
			for (int i = 0;i < len;i++){
				int x = v[i];
				if (status[x]) dele(x,0);
		 	}
	 	}
 	}
}

int main(){
	#ifdef LOCAL_DEFINE
	    freopen("F:\\c++source\\rush_in.txt", "r", stdin);
	#endif
	ios::sync_with_stdio(0),cin.tie(0);

	while (getline(cin,s)){
		yilai.clear(),beiyilai.clear(),
		status.clear(),dic.clear();dic2.clear();
		installed.clear();
	 	while (s!="END"){
	 		cout << s << endl;
			stringstream ss(s);
			ss >> ope;
			if (ope=="INSTALL"){
			 	string x;
			 	ss >> x;
			 	pd(x);
			 	int y = dic[x];
			 	if (status[y]!=0)
			 		cout <<"   "<<x<<" is already installed."<<endl;
			 	else
			 		ins(y,1);
		 	}else if (ope=="REMOVE"){
		 	 	string x;
		 	 	ss >> x;
		 	 	pd(x);
		 	 	int y = dic[x];
		 	 	if (status[y]==0)
		 	 		cout <<"   "<<x<<" is not installed."<<endl;
				else if (need(y))
					cout <<"   "<<x<<" is still needed."<<endl;
					else{
					 	dele(y,1);
					}
		 	}else if (ope=="LIST"){
		 		for (int x:installed){
		 		 	cout <<"   "<<dic2[x]<<endl;
		 		}
		 	}else{
				//depend
				string x,y;int xx,yy;
				ss >> x;
				pd(x);xx = dic[x];
				while (ss>>y){
				 	pd(y);yy = dic[y];
				 	yilai[xx].push_back(yy);
				 	beiyilai[yy].push_back(xx);
				}
		 	}
	 		getline(cin,s);
		}
		cout << s << endl;
	}

	return 0;
}