基于STL的字典生成模块-模拟搜索引擎算法的尝试

该课题来源于UVA中Searching the Web的题目：https://vjudge.net/problem/UVA-1597

按照题目的说法，我对按照特定格式输入的文章中的词语合成字典，以满足后期的快速查找。

针对于字典的合成途径，我利用了STL中的map与set的嵌套形成了一种特定的数据结构来解析文章中的单词

 #include<map>
 #include<iostream>
 #include<set>
 #include<algorithm>
 #include<string>
 #include<cctype>
 #include<sstream>
 using namespace std;
 struct newpair
 {
     int article;
     int line;
     bool operator<(const newpair b) const
     {
         return this->line < b.line;
     }
 };
 typedef map<string,set<newpair> > BIGMAP;
 typedef set<newpair>::iterator SET_pair_ITER;
 typedef map<string,set<newpair> >::iterator BIGMAP_iter;

 BIGMAP maper;
 string psd[];
 int maxline;

 int checkmaper()
 {
     BIGMAP_iter it;
     for(it=maper.begin();it!=maper.end();++it)
     {
         cout<<(it->first);//string-type
         set<newpair> cyc;
         cyc=it->second;//set<newpair>-type
         for(SET_pair_ITER iter=cyc.begin();iter!=cyc.end();++iter)
         {
             newpair ctn=*iter;
             cout<<"  article "<<ctn.article<<" line "<<ctn.line<<endl;
         }
     }
     return ;
 }

 void buildmaper(string aim,int articlenum,int linenum)
 {
     newpair m;
     m.article=articlenum;
     m.line=linenum;
     maper[aim].insert(m);
 }

 int readin()
 {
     int n;
     char c;//input the \n
     cin>>n>>c;
     int cur=;
     for(int i=;i<n;cur++)
     {
         getline(cin,psd[cur]);
         if((int)psd[cur].find("***")!=-){i++;continue;}//the next article
         for(string::iterator it=psd[cur].begin();it!=psd[cur].end();++it)
         {
             if(isalpha(*it)) *it=tolower(*it);
             else *it=' ';
         }
         stringstream ss(psd[cur]);
         string chr;
         while(ss>>chr) buildmaper(chr,i,cur);
     }
     return cur;
 }

 int main()
 {
     freopen("input.txt","r",stdin);
     freopen("ans.txt","w",stdout);
     maxline=readin();
     checkmaper();
     return ;
 }

以上代码涉及了较多C++知识与个别底层知识，下面进行列举：

1、stringstream常用操作

2、基本STL之map与set

3、结构体中的运算符重载

4、迭代器的操作

5、RB树实现map与set的基本原理

有关详细的实现方法请参照我的其它博客和上述代码。

在上述代码中唯一一个容易出现bug的位置是set的实现：由于set对输入的元素需要进行排序，所以必须在newpair结构体中重载<(operator)。

下面是运行图片：

输入如下：

one   repeat  repeat  repeat
A manufacturer, importer, or seller of
digital media devices may not () sell,
or offer for sale, in interstate commerce,
or () cause to be transported in, or in a
manner affecting, interstate commerce,
a digital media device unless the device
includes and utilizes standard security
technologies that adhere to the security
system standards.
**********
one two   repeat  repeat  repeat   repeat
Of course, Lisa did not necessarily
intend to read his books. She might
want the computer only to write her
midterm. But Dan knew she came from
a middle-class family and could hardly
afford the tuition, let alone her reading
fees. Books might be the only way she
could graduate
**********
one two three   repeat   repeat  repeat  repeat   repeat
Research in analysis (i.e., the evaluation
of the strengths and weaknesses of
computer system) is essential to the
development of effective security, both
for works protected by copyright law
and for information in general. Such
research can progress only through the
open publication and exchange of
complete scientific results
**********
one two three   four   repeat  repeat   repeat  repeat  repeat   repeat
I am very very very happy!
What about you?
**********

输出如下：

a  article  line
  article  line
  article  line
  article  line
about  article  line
adhere  article  line
affecting  article  line
afford  article  line
alone  article  line
am  article  line
analysis  article  line
and  article  line
  article  line
  article  line
  article  line
  article  line
be  article  line
  article  line
books  article  line
  article  line
both  article  line
but  article  line
by  article  line
came  article  line
can  article  line
cause  article  line
class  article  line
commerce  article  line
  article  line
complete  article  line
computer  article  line
  article  line
copyright  article  line
could  article  line
  article  line
course  article  line
dan  article  line
development  article  line
device  article  line
devices  article  line
did  article  line
digital  article  line
  article  line
e  article  line
effective  article  line
essential  article  line
evaluation  article  line
exchange  article  line
family  article  line
fees  article  line
for  article  line
  article  line
  article  line
four  article  line
from  article  line
general  article  line
graduate  article  line
happy  article  line
hardly  article  line
her  article  line
  article  line 17

其余略。。。。。。。。。。

OK