UVA 230 Borrowers （STL 行读入的处理 重载小于号）

题意：

输入若干书籍和作者名字，然后先按作者名字升序排列，再按标题升序排列，然后会有3种指令，BORROW,RETURN, SHELVE。

BORROW 和 RETURN 都会带有一个书名在后面，如：

BORROW "The Canterbury Tales"
RETURN "The Canterbury Tales"

当遇到SHELVE指令，输出已还但没上架的书排序后（规则同上）依次插入书架的序列。

用例：

输入：

"The Canterbury Tales" by Chaucer, G.
"Algorithms" by Sedgewick, R.
"The C Programming Language" by Kernighan, B. and Ritchie, D.
END
BORROW "The Canterbury Tales"
RETURN "The Canterbury Tales"
BORROW "The C Programming Language"
RETURN "The C Programming Language"
SHELVE
BORROW "Algorithms"
RETURN "Algorithms"
SHELVE
END

输出：

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

分析：

这题的读入有点麻烦，我的处理是使用getline， 然后将 “ 号变成空格 将空格变成“#”（ASCII差距不大）， 再用stringsteam输入到string中，最后输出再将“#”转换为“ ”。

网上的方法是使用string.substr()截取,用string.find()去寻找位置， 我截取这种方法更好（stringsteam很慢）。

用map<string,int>将string映射到书架位置上面，用一个bool去标记这个位置有没被拿走，注意return后不能直接把书放回去，要标记，等收到SHELVE指令再排序放书。

#include <cstdio>
#include <cstring>
#include <vector>
#include <map>
#include <string>
#include <iostream>
#include <set>
#include <sstream>
#include <algorithm>
using namespace std;
struct B
{
    string name;
    string author;
    B(){}
    B(const string& _name,const string& _author):
        name(_name),author(_author){}
    friend bool operator < (const B a,const B b)
    {
        if(a.author < b.author) return true;
        else
        {
            if(a.author == b.author)
            {
                if(a.name < b.name)
                    return true;
                else return false;
            }
            else return false;
        }
    }
};
struct A
{
    int a;
    int b;
    A(){}
    A(int _a, int _b):
        a(_a), b(_b){}
//    a after b of a is the first(b=-1);
};
typedef set<B> :: iterator sIT;
typedef vector<B> :: iterator vIT;
typedef vector<A> :: iterator aIT;
typedef vector<int> :: iterator IT;
string trans(const string& a)
{
    string t = a;
    for(int i = 0; i < t.size(); i++)
    {
        if(t[i] == '#') t[i] = ' ';
    }
    return t;
}
int main()
{
    ios::sync_with_stdio(false);
    #if LOCAL
    freopen("1.txt","r",stdin);
    freopen("2.txt","w",stdout);
    #endif // LOCAL
    string s;
    vector<B> book;
    bool lend[1005];
    vector<A> ans;
    fill(lend, lend+1005,1);
    map<string,int> id;
    vector<int> ret;
    while(getline(cin,s))
    {
        for(int i = 0; i < s.size(); i++)
        {
            if(s[i] == '"') s[i] = ' ';
            else if(s[i] == ' ') s[i] = '#';
        }
        stringstream ss(s);
        string tname, tauthor;
        if(!(ss>>tname>>tauthor)) break;
        book.push_back(B(tname,tauthor));
    }
    sort(book.begin(), book.end());
    int cnt = 0;
    for(vIT it = book.begin(); it != book.end(); it++)
    {
        id[(*it).name] = cnt++;
    }
    string op;
    while(cin>>op)
    {
        if(op=="END") break;
        if(op == "SHELVE")
        {
            sort(ret.begin(), ret.end());
            for(IT it = ret.begin(); it != ret.end(); it++)
            {
                lend[*it] = 1;
                int c = (*it) -1;
                for(; c >= 0 && lend[c] == 0; c--);
                ans.push_back(A(*it,c));
            }
            ret.clear();
            for(aIT it = ans.begin(); it != ans.end(); it++)
            {
                if((*it).b != -1)
                {
                    cout<<"Put ""<< trans(book[(*it).a].name) << "" after "" << trans(book[(*it).b].name) << ""
";

                }
                else
                {
                    cout<<"Put ""<<trans(book[(*it).a].name)<< "" first"<<"
";

                }
            }
            ans.clear();
            cout<<"END
";
            continue;
        }
        cin.ignore();
        string b;
        getline(cin,b);
        for(int i = 0; i < b.size(); i++)
        {
            if(b[i] == '"') b[i] = ' ';
            else if(b[i] == ' ') b[i] = '#';
        }
        stringstream ss(b);
        ss>>b;
        if(op== "BORROW")
        {
            lend[id[b]] = 0;
        }
        else if(op == "RETURN")
        {

            ret.push_back(id[b]);
        }
    }


    return 0;
}