算法习题---5-8图书管理系统*****<双向迭代器>（UVa230）

一：题目

就是输入一系列书本名和作者名，然后输入命令模拟借书和还书，再输出归还的书的摆放位置。要求有两点：

需要对归还的书做特殊排序处理：作者名相同，则书本按书名从小到大排序；否则书本按作者名大小排序
需要归还的书的位置前面没有书籍时，需要特殊处理

（一）样例输入

"The Canterbury Tales" by Chaucer, G.
"Algorithms" by Sedgewick, R.
"The C Programming Language" by Kernighan, B. and Ritchie, D.
END　　　　//结束信息录入
BORROW "Algorithms"
BORROW "The C Programming Language"　　//借书
RETURN "Algorithms"　　　　　　　　　　　　//还书
RETURN "The C Programming Language"
SHELVE　　　　//打印提示信息
END　　　　//结束

（二）样例输出

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

（三）更多测试样例：推荐https://www.jianshu.com/p/902295e378a5

二：代码实现

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <map>　　//重点：map,set支持双向迭代
#include <vector>
#include <string>
#include <iterator>

using namespace std;

map<string, map<string,int> >Books;    //是支持双向迭代的,用于存放<作者，<书名，借阅状态>>
map<string, string>Title_Author;    //用于映射<书名，作者>
vector<string> Books_Title;            //存放所有要归还的书名

int main()
{
    freopen("data5_8_h.in", "r", stdin);
    freopen("data5_8_h.out", "w", stdout);

    string book_t, book_a,all_info;
    //获取图书信息
    while (getline(cin, all_info)&&all_info!="END")
    {
        int start, end;
        start = all_info.find('"');
        end = all_info.find('"', start + 1);
        book_t = all_info.substr(start + 1, end - start -1);
        start = all_info.find("by ");
        book_a = all_info.substr(start + 3);
        
        if (!Books.count(book_a))
            Books[book_a] = map<string, int>();
        (Books[book_a])[book_t] = 1;
        Title_Author[book_t] = book_a;
    }
    
    //进行图书借阅
    while (cin >> all_info&&all_info != "END")
    {
        if (all_info[0] == 'B')    //借书
        {
            getline(cin, book_t);
            book_t = book_t.substr(book_t.find('"') + 1, book_t.rfind('"') - book_t.find('"')-1);
            book_a = Title_Author[book_t];
            
            Books[book_a][book_t] = -1;
        }
        else if (all_info[0] == 'R')    //还书
        {
            getline(cin, book_t);
            book_t = book_t.substr(book_t.find('"') + 1, book_t.rfind('"') - book_t.find('"')-1);
            Books_Title.push_back(book_t);
        }
        else if (all_info[0] == 'S')    //入库
        {
            for (int i = Books_Title.size() - 1; i >= 0; i--)
            {
                book_t = Books_Title[i];
                Books_Title.pop_back();
                book_a = Title_Author[book_t];
                //在当前自己作者下找
                map<string, map<string, int> >::iterator a_rit = Books.find(book_a);
                for (; a_rit != Books.end(); a_rit--)　　　　　　//如何对双向迭代器进行结束判断？？疑惑---有时间调试一下
                {
                    //进行书籍操作
                    bool flag = false;
                    map<string, int>::iterator t_rit = a_rit->second.find(book_t);
                    for (; t_rit-- != (a_rit->second).begin();)　　//疑惑：若是使用上面迭代的形式；t_rit != (a_rit->second).end();t_rit--则输出数据不一致
                    {
                        if (t_rit->second == 1)
                        {
                            cout << "PUT "" << book_t << "" after "" << t_rit->first << """ << endl;
                            (*(Books[book_a]).find(book_t)).second = 1;
                            flag = true;
                            break;
                        }
                    }
                    if (flag)
                        break;
                }
                if (a_rit == Books.end())
                {
                    (*(Books[book_a]).find(book_t)).second = 1;
                    cout << "PUT "" << book_t << "" first" << endl;
                }
            }
            cout << "END" << endl;
        }
    }

    freopen("CON", "r", stdin);
    freopen("CON", "w", stdout);
    return 0;
}