I mean your borrowers of books — those mutilators of collections, spoilers of the symmetry of shelves, and creators of odd volumes.

– (Charles Lamb, Essays of Elia (1823) ‘The Two Races of Men’)

  Like Mr. Lamb, librarians have their problems with borrowers too. People don’t put books back where they should. Instead, returned books are kept at the main desk until a librarian is free to replace them in the right places on the shelves. Even for librarians, putting the right book in the right place can be very time-consuming. But since many libraries are now computerized, you can write a program to help.

  When a borrower takes out or returns a book, the computer keeps a record of the title. Periodically, the librarians will ask your program for a list of books that have been returned so the books can be returned to their correct places on the shelves. Before they are returned to the shelves, the returned books are sorted by author and then title using the ASCII collating sequence. Your program should output the list of returned books in the same order as they should appear on the shelves. For each book, your program should tell the librarian which book (including those previously shelved) is already on the shelf before which the returned book should go.

Input

  First, the stock of the library will be listed, one book per line, in no particular order. Initially, they are all on the shelves. No two books have the same title. The format of each line will be:

"title" by author

  The end of the stock listing will be marked by a line containing only the word:

END

  Following the stock list will be a series of records of books borrowed and returned, and requests from librarians for assistance in restocking the shelves. Each record will appear on a single line, in one of the following formats:

BORROW title

RETURN title

SHELVE

  The list will be terminated by a line containing only the word:

END

  Each time the SHELVE command appears, your program should output a series of instructions for the librarian, one per line, in the format:

Put _title_1 after _title_2 or, for the special case of the book being the first in the collection:

Put title first

After the set of instructions for each SHELVE, output a line containing only the word:

END

Assumptions & Limitations:

1. A title is at most 80 characters long.

2. An author is at most 80 characters long.

3. A title will not contain the double quote (") character.

"The Canterbury Tales" by Chaucer, G.
"The Canterbury Taless" by Chaucer, B.
"Algorithms" by Sedgewick, R.
"The C Programming Language" by Kernighan, B. and Ritchiee, D.
"The C Programming Languag" by Kernighan, B. and Ritchiee, D.
"The D Programming Language" by Kernighan, B. and Ritchiee, D.
"A House for Mr. Biswas" by Naipaul, V.S.
"A Congo Diary" by Naipaul, V.S.
END
BORROW "Algorithms"
BORROW "The C Programming Language"
BORROW "The C Programming Languag"
BORROW "The Canterbury Taless"
SHELVE
RETURN "Algorithms"
RETURN "The Canterbury Taless"
SHELVE
RETURN "The C Programming Languag"
SHELVE
BORROW "The C Programming Languag"
BORROW "The Canterbury Taless"
BORROW "A House for Mr. Biswas"
RETURN "The Canterbury Taless"
SHELVE
RETURN "The C Programming Language"
RETURN "A House for Mr. Biswas"
SHELVE
END



Put "The C Programming Language" after "The Canterbury Tales"
Put "Algorithms" after "The C Programming Language"
END

使用结构体数组进行操作。定义一个结构体，成员为头作者和书名两个字符串。排序使用sort(),但要自己定义排序方法。另外，借出书籍的时候，要想定位并删除此元素要自己定义一个指针，使用find()函数无法对结构体进行比较，在结构体里面重载运算符应该是可以的，但小白表示不会。。。所以定义一个auto指针来查找。因为输出书名需要双引号所以存入就不去除双引号了。

整体的框架很好理解，录入书籍整行读取，然后分割书名和作者。然后读入指令，对指令区分操作，小细节还是比较多的，具体看代码。

#include<bits/stdc++.h>
using namespace std;
struct books {
    string title;       //书名
    string name;        //作者
};
bool compare(books a, books b) {    //自定义的排序方法，用于sort
    if (a.name == b.name)return a.title < b.title;
    return a.name < b.name;
}
int main(){
    vector<books>list;      //目前书架上的书籍
    vector<books>ret;       //归还的书籍
    map<string, string>alllist; //存储书籍副本
    string s,title;books temp;
    while (getline(cin, s) && s != "END") {         //录入书籍信息
        int i=s.find('\"',1);           //对书籍进行分割
        temp.title = s.substr(0, i+1);
        temp.name = s.substr(i + 1, s.size() - 1);
        list.push_back(temp);           //存入数组并且保存map副本
        alllist[temp.title] = temp.name;
    }
    while (cin>>s&&s!="END"){
        if (s == "SHELVE") {            //对未上架的图书上架处理
            sort(ret.begin(), ret.end(), compare);  //排序
            for (int i = 0;i < ret.size();i++) {    //挨个书籍处理
                temp = ret[i];
                list.push_back(temp);               //上架
                sort(list.begin(), list.end(), compare);//排序
                for (int i = 0;i < list.size();i++) {   //查找并输出
                    if (list[i].name == temp.name && list[i].title == temp.title) {
                        if(i==0)cout << "Put " << temp.title << " first" << endl;
                        else cout << "Put " << temp.title << " after " << list[i-1].title << endl;
                        break;
                    }
                }
            }
            ret.clear();        //每次输出完毕必须清空记录，一面影响下一次的使用
            cout << "END" << endl;
        }
        else {
            getchar();          //吃掉空格
            getline(cin, title);//读入标题
            temp.title = title; //保存到临时结构体
            temp.name = alllist[title];
            if (s == "BORROW") {
                auto pointer = list.begin();//本来使用find()函数不会重载所以自己定义指针查找
                while (!((*pointer).title == temp.title))pointer++;
                list.erase(pointer);        //删除
            }
            else if (s == "RETURN")ret.push_back(temp);//记录还书信息
        }
    }
}