<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">题目思路：</span>
<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">首先需要构造出关键词的字典，提取关键字有一个小技巧：可以把字符串中所有非英文字母化为空格，然后用stringstream读取</span>
void updatedic(string str,int doc_id,int row_id)
{
string word;
for(int i=0;i<str.size();i++)
{
if(isalpha(str[i]))
str[i]=tolower(str[i]);
else
str[i]=' ';
}
stringstream s(str);
while(s>>word)
dic[word].insert(pair<int,int>(doc_id,row_id));
}然后根据查询的关键字分别处理，这里可以用到stl中的set_union和set_intersection函数进行求交集和并集，完整代码如下：
#include <iostream>
#include <fstream>
#include <string>
#include <map>
#include <vector>
#include <sstream>
#include <set>
#include <algorithm>
#include <iterator>
using namespace std;
map<string ,set<pair<int,int>>> dic;
vector<vector<string>> doc;
#define FILE
void updatedic(string str,int doc_id,int row_id)
{
string word;
for(int i=0;i<str.size();i++)
{
if(isalpha(str[i]))
str[i]=tolower(str[i]);
else
str[i]=' ';
}
stringstream s(str);
while(s>>word)
dic[word].insert(pair<int,int>(doc_id,row_id));
}
void get_doc_id(set<pair<int,int>>table,set<int> &res)
{
for(set<pair<int,int>>::iterator it=table.begin();it!=table.end();it++)
{
res.insert((*it).first);
}
}
int main(int argc, char* argv[])
{
#ifdef FILE
ifstream in("data.txt");
ofstream out("output.txt");
cin.rdbuf(in.rdbuf());
cout.rdbuf(out.rdbuf());
#endif
int N,M;
string str;
while(cin>>N)
{
cin.get();
int doc_id=0;
for(int i=0;i<N;i++)
{
int row_id=0;
while(getline(cin,str))
{
if(str=="**********")
break;
else
{
if(doc_id==doc.size())
{
vector<string> temp;
doc.push_back(temp);
}
doc[doc_id].push_back(str);
updatedic(str,doc_id,row_id);
row_id++;
}
}
doc_id++;
}
cin>>M;
cin.get();
for(int i=0;i<M;i++)
{
getline(cin,str);
if(str[0]=='N')
{
string keyword = str.substr(4);
set<pair<int,int>>table = dic[keyword];
if(table.size()==doc.size())
{
cout<<"Sorry, I found nothing."<<endl<<"=========="<<endl;
continue;
}
map<int,int>res;
for(set<pair<int,int>>::iterator it=table.begin();it!=table.end();it++)
{
pair<int,int> val= *it;
res[val.first] = 1;
}
int num =0,doc_num=0 ;
for(int i=0;i<doc.size();i++)
{
if(res.count(i)==0)
{
if(num!=0)
{
if(doc_num!=i)
{
cout<<"----------"<<endl;
doc_num=i;
}
}
num++;
for(int j=0;j<doc[i].size();j++)
{
cout<<doc[i][j]<<endl;
}
}
}
cout<<"=========="<<endl;
}
else if(str.find("AND")!=string::npos)
{
int p = str.find("AND");
string keyword1 = str.substr(0,p-1),keyword2 = str.substr(p+4);
set<pair<int,int>>table1 = dic[keyword1];
set<pair<int,int>>table2 = dic[keyword2];
set<pair<int,int>>res;
set<int> table,table1_temp,table2_temp;
get_doc_id(table1,table1_temp);
get_doc_id(table2,table2_temp);
set_intersection(table1_temp.begin(),table1_temp.end(),table2_temp.begin(),table2_temp.end(),inserter(table,table.begin()));
set_union(table1.begin(),table1.end(),table2.begin(),table2.end(),inserter(res,res.begin()));
if(table.size()==0)
{
cout<<"Sorry, I found nothing."<<endl<<"=========="<<endl;
continue;
}
int doc_num=*(table.begin()),i=0;
for(set<int>::iterator it=table.begin();it!=table.end();it++)
{
if(i!=0)
{
if((*it)!=doc_num)
{
cout<<"----------"<<endl;
doc_num = *it;
}
}
for(int j=0;j<doc[*it].size();j++)
{
if(res.find(pair<int,int>(*it,j))!=res.end())
{
cout<<doc[*it][j]<<endl;
i++;
}
}
}
cout<<"=========="<<endl;
}
else if(str.find("OR")!=string::npos)
{
int p = str.find("OR");
string keyword1 = str.substr(0,p-1),keyword2 = str.substr(p+3);
set<pair<int,int>>table1 = dic[keyword1];
set<pair<int,int>>table2 = dic[keyword2];
set<pair<int,int>>res ;
set_union(table1.begin(),table1.end(),table2.begin(),table2.end(),inserter(res,res.begin()));
if(res.size()==0)
{
cout<<"Sorry, I found nothing."<<endl<<"=========="<<endl;
continue;
}
int i =0;
int doc_num=(*res.begin()).first;
for(set<pair<int,int>>::iterator it=res.begin();it!=res.end();it++,i++)
{
pair<int,int> val= *it;
if(i!=0)
{
if(val.first!=doc_num)
{
cout<<"----------"<<endl;
doc_num = val.first;
}
}
cout<<doc[val.first][val.second]<<endl;
}
cout<<"=========="<<endl;
}
else
{
string keyword = str;
set<pair<int,int>>table = dic[keyword];
if(table.size()==0)
{
cout<<"Sorry, I found nothing."<<endl<<"=========="<<endl;
continue;
}
int i =0,doc_num=(*table.begin()).first;
for(set<pair<int,int>>::iterator it=table.begin();it!=table.end();it++,i++)
{
pair<int,int> val= *it;
if(i!=0)
{
if(doc_num!=val.first)
{
cout<<"----------"<<endl;
doc_num=val.first;
}
}
cout<<doc[val.first][val.second]<<endl;
}
cout<<"=========="<<endl;
}
}
dic.clear();
doc.clear();
}
return 0;
}
