UVA 230 Borrowers （STL 行读入的处理 重载小于号）

Posted 2020-09-19 Neord

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。

 

  1 #include <cstdio>
  2 #include <cstring>
  3 #include <vector>
  4 #include <map>
  5 #include <string>
  6 #include <iostream>
  7 #include <set>
  8 #include <sstream>
  9 #include <algorithm>
 10 using namespace std;
 11 struct B
 12 {
 13     string name;
 14     string author;
 15     B(){}
 16     B(const string& _name,const string& _author):
 17         name(_name),author(_author){}
 18     friend bool operator < (const B a,const B b)
 19     {
 20         if(a.author < b.author) return true;
 21         else
 22         {
 23             if(a.author == b.author)
 24             {
 25                 if(a.name < b.name)
 26                     return true;
 27                 else return false;
 28             }
 29             else return false;
 30         }
 31     }
 32 };
 33 struct A
 34 {
 35     int a;
 36     int b;
 37     A(){}
 38     A(int _a, int _b):
 39         a(_a), b(_b){}
 40 //    a after b of a is the first(b=-1);
 41 };
 42 typedef set<B> :: iterator sIT;
 43 typedef vector<B> :: iterator vIT;
 44 typedef vector<A> :: iterator aIT;
 45 typedef vector<int> :: iterator IT;
 46 string trans(const string& a)
 47 {
 48     string t = a;
 49     for(int i = 0; i < t.size(); i++)
 50     {
 51         if(t[i] == ‘#‘) t[i] = ‘ ‘;
 52     }
 53     return t;
 54 }
 55 int main()
 56 {
 57     ios::sync_with_stdio(false);
 58     #if LOCAL
 59     freopen("1.txt","r",stdin);
 60     freopen("2.txt","w",stdout);
 61     #endif // LOCAL
 62     string s;
 63     vector<B> book;
 64     bool lend[1005];
 65     vector<A> ans;
 66     fill(lend, lend+1005,1);
 67     map<string,int> id;
 68     vector<int> ret;
 69     while(getline(cin,s))
 70     {
 71         for(int i = 0; i < s.size(); i++)
 72         {
 73             if(s[i] == ‘"‘) s[i] = ‘ ‘;
 74             else if(s[i] == ‘ ‘) s[i] = ‘#‘;
 75         }
 76         stringstream ss(s);
 77         string tname, tauthor;
 78         if(!(ss>>tname>>tauthor)) break;
 79         book.push_back(B(tname,tauthor));
 80     }
 81     sort(book.begin(), book.end());
 82     int cnt = 0;
 83     for(vIT it = book.begin(); it != book.end(); it++)
 84     {
 85         id[(*it).name] = cnt++;
 86     }
 87     string op;
 88     while(cin>>op)
 89     {
 90         if(op=="END") break;
 91         if(op == "SHELVE")
 92         {
 93             sort(ret.begin(), ret.end());
 94             for(IT it = ret.begin(); it != ret.end(); it++)
 95             {
 96                 lend[*it] = 1;
 97                 int c = (*it) -1;
 98                 for(; c >= 0 && lend[c] == 0; c--);
 99                 ans.push_back(A(*it,c));
100             }
101             ret.clear();
102             for(aIT it = ans.begin(); it != ans.end(); it++)
103             {
104                 if((*it).b != -1)
105                 {
106                     cout<<"Put \""<< trans(book[(*it).a].name) << "\" after \"" << trans(book[(*it).b].name) << "\"\n";
107 
108                 }
109                 else
110                 {
111                     cout<<"Put \""<<trans(book[(*it).a].name)<< "\" first"<<"\n";
112 
113                 }
114             }
115             ans.clear();
116             cout<<"END\n";
117             continue;
118         }
119         cin.ignore();
120         string b;
121         getline(cin,b);
122         for(int i = 0; i < b.size(); i++)
123         {
124             if(b[i] == ‘"‘) b[i] = ‘ ‘;
125             else if(b[i] == ‘ ‘) b[i] = ‘#‘;
126         }
127         stringstream ss(b);
128         ss>>b;
129         if(op== "BORROW")
130         {
131             lend[id[b]] = 0;
132         }
133         else if(op == "RETURN")
134         {
135 
136             ret.push_back(id[b]);
137         }
138     }
139 
140 
141     return 0;
142 }