Uva

AC代码：

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cstring>
#include <string>
#include <sstream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <stack>
#include <queue>

using namespace std;

// 这里用struct也可以
class book
{
public:
	book(string t, string a) { author = a; title = t; borrowed = returned = false; }
	bool borrowed, returned;
	string author, title;
};

vector<book> all;
string in, command, req;

void shelve(), borrow(), back();

bool cmpa(book a, book b){ return (a.author < b.author); }
bool cmpt(book a, book b){ return (a.title < b.title); }

int main()
{
	while (getline(cin, in) && in != "END")
		all.push_back(book(in.substr(0, in.find_last_of(""") + 1),
		in.substr(in.find_last_of(""") + 1)));
	stable_sort(all.begin(), all.end(), cmpt);
	stable_sort(all.begin(), all.end(), cmpa);

	while (cin >> command)
		if (command == "BORROW")
			cin.get(), borrow();
		else if (command == "RETURN")
			cin.get(), back();
		else if (command == "SHELVE")
			cin.get(), shelve();
}

void shelve()
{
	for (int i = 0, j; i < all.size(); ++i)
		if (all[i].returned == true)
		{
			for (j = i; j >= 0; --j)
				if (all[j].borrowed == false)
					break;
			if (j == -1)
				printf("Put %s first
", all[i].title.c_str());
			else
				printf("Put %s after %s
", all[i].title.c_str(), all[j].title.c_str());
			all[i].borrowed = all[i].returned = false;
		}
	cout << "END
";
}
void borrow()
{
	getline(cin, req);
	for (int i = 0; i < all.size(); i++)
		if (all[i].title == req)
		{
			all[i].borrowed = true;
			return;
		}
}
void back()
{
	getline(cin, req);
	for (size_t i = 0; i < all.size(); i++)
		if (all[i].title == req)
		{
			all[i].returned = true;
			return;
		}
}