本文介绍了一个图书检索系统的实现方法，该系统可以根据读者提供的查询条件，如书名、作者、关键词等，快速查找并按图书ID升序排列输出相关书籍。文章提供了三种不同的实现方案，包括使用multimap结合额外排序、利用map与set组合以及简单的线性搜索方法。
Pat1022代码
题目描述：
A Digital Library contains millions of books, stored according to their titles, authors, key words of their abstracts, publishers, and published years. Each book is assigned an unique 7-digit number as its ID. Given any query from a reader, you are supposed to output the resulting books, sorted in increasing order of their ID's.
Input Specification:
Each input file contains one test case. For each case, the first line contains a positive integer N (<=10000) which is the total number of books. Then N blocks follow, each contains the information of a book in 6 lines:
- Line #1: the 7-digit ID number;
- Line #2: the book title -- a string of no more than 80 characters;
- Line #3: the author -- a string of no more than 80 characters;
- Line #4: the key words -- each word is a string of no more than 10 characters without any white space, and the keywords are separated by exactly one space;
- Line #5: the publisher -- a string of no more than 80 characters;
- Line #6: the published year -- a 4-digit number which is in the range [1000, 3000].
It is assumed that each book belongs to one author only, and contains no more than 5 key words; there are no more than 1000 distinct key words in total; and there are no more than 1000 distinct publishers.
After the book information, there is a line containing a positive integer M (<=1000) which is the number of user's search queries. Then M lines follow, each in one of the formats shown below:
- 1: a book title
- 2: name of an author
- 3: a key word
- 4: name of a publisher
- 5: a 4-digit number representing the year
Output Specification:
For each query, first print the original query in a line, then output the resulting book ID's in increasing order, each occupying a line. If no book is found, print "Not Found" instead.
Sample Input:3 1111111 The Testing Book Yue Chen test code debug sort keywords ZUCS Print 2011 3333333 Another Testing Book Yue Chen test code sort keywords ZUCS Print2 2012 2222222 The Testing Book CYLL keywords debug book ZUCS Print2 2011 6 1: The Testing Book 2: Yue Chen 3: keywords 4: ZUCS Print 5: 2011 3: blablablaSample Output:
1: The Testing Book 1111111 2222222 2: Yue Chen 1111111 3333333 3: keywords 1111111 2222222 3333333 4: ZUCS Print 1111111 5: 2011 1111111 2222222 3: blablabla Not Found
考虑到用multimap来做，但是相同键值的元素顺序不确定，还要进行一次排序，复杂度与排序算法有关,结果最后一个case运行超时。。。
#include<cstdio>
#include<cstdlib>
#include<string>
#include<iostream>
#include<map>
#include<vector>
#include<algorithm>
using namespace std;
bool cmp(const string &l,const string &r)
{
if(l<r)
return true;
else
return false;
}
int main(int argc,char *argv[])
{
int n,m;
int i,j;
multimap<string,string> title;
multimap<string,string> author;
multimap<string,string> keyword;
multimap<string,string> publisher;
multimap<string,string> year;
scanf("%d",&n);
getchar();//吸收回车符
for(i=0;i<n;i++)
{
string num,name;
string writer,word;
string puber,time;
getline(cin,num);
getline(cin,name);
getline(cin,writer);
while(1)//截取一个单词
{
string word;
cin>>word;
keyword.insert(pair<string,string>(word,num));
if(getchar()=='\n')
break;
}
getline(cin,puber);
getline(cin,time);
title.insert(pair<string,string>(name,num));
author.insert(pair<string,string>(writer,num));
publisher.insert(pair<string,string>(puber,num));
year.insert(pair<string,string>(time,num));
}
scanf("%d",&m);
getchar();
for(i=0;i<m;i++)
{
int choice;
string query;
int flag=0;
vector<string> v;
map<string,string>::iterator it;
scanf("%d: ",&choice);
getline(cin,query);
cout<<choice<<": "<<query<<endl;
switch(choice)
{
case 1:
for(it=title.begin();it!=title.end();it++)
{
if(it->first==query)
{
flag=1;
v.push_back(it->second);
}
}
if(!flag)
cout<<"Not Found"<<endl;
break;
case 2:
for(it=author.begin();it!=author.end();it++)
{
if(it->first==query)
{
flag=1;
v.push_back(it->second);
}
}
if(!flag)
cout<<"Not Found"<<endl;
break;
case 3:
for(it=keyword.begin();it!=keyword.end();it++)
{
if(it->first==query)
{
flag=1;
v.push_back(it->second);
}
}
if(!flag)
cout<<"Not Found"<<endl;
break;
case 4:
for(it=publisher.begin();it!=publisher.end();it++)
{
if(it->first==query)
{
flag=1;
v.push_back(it->second);
}
}
if(!flag)
cout<<"Not Found"<<endl;
break;
case 5:
for(it=year.begin();it!=year.end();it++)
{
if(it->first==query)
{
flag=1;
v.push_back(it->second);
}
}
if(!flag)
cout<<"Not Found"<<endl;
break;
}
sort(v.begin(),v.end(),cmp);//键值相等的元素的位置是无序的
vector<string>::iterator iter;//所以要进行排序
for(iter=v.begin();iter!=v.end();iter++)
cout<<*iter<<endl;
}
return 0;
}
将map与set结合起来，这样就不用进行排序了，复杂度低于方法一。
AC代码：
#include<cstdio>
#include<cstdlib>
#include<string>
#include<iostream>
#include<map>
#include<set>
#include<algorithm>
using namespace std;
int main(int argc,char *argv[])
{
int n,m;
int i,j;
map<string,set<string> > title;
map<string,set<string> > author;
map<string,set<string> > keyword;
map<string,set<string> > publisher;
map<string,set<string> > year;
map<string,set<string> >::iterator it;
scanf("%d",&n);
getchar();
for(i=0;i<n;i++)
{
string num,name;
string writer,word;
string puber,time;
getline(cin,num);
getline(cin,name);
getline(cin,writer);
while(1)
{
string word;
cin>>word;
keyword[word].insert(num);
if(getchar()=='\n')
break;
}
getline(cin,puber);
getline(cin,time);
title[name].insert(num);
author[writer].insert(num);
publisher[puber].insert(num);
year[time].insert(num);
}
scanf("%d",&m);
getchar();
for(i=0;i<m;i++)
{
int choice;
string query;
set<string>::iterator pos;
scanf("%d: ",&choice);
getline(cin,query);
cout<<choice<<": "<<query<<endl;
switch(choice)
{
case 1:
it=title.find(query);
if(it==title.end())
cout<<"Not Found"<<endl;
else
{
for(pos=it->second.begin();pos!=it->second.end();pos++)
cout<<*pos<<endl;
}
break;
case 2:
it=author.find(query);
if(it==author.end())
cout<<"Not Found"<<endl;
else
{
for(pos=it->second.begin();pos!=it->second.end();pos++)
cout<<*pos<<endl;
}
break;
case 3:
it=keyword.find(query);
if(it==keyword.end())
cout<<"Not Found"<<endl;
else
{
for(pos=it->second.begin();pos!=it->second.end();pos++)
cout<<*pos<<endl;
}
break;
case 4:
it=publisher.find(query);
if(it==publisher.end())
cout<<"Not Found"<<endl;
else
{
for(pos=it->second.begin();pos!=it->second.end();pos++)
cout<<*pos<<endl;
}
break;
case 5:
it=year.find(query);
if(it==year.end())
cout<<"Not Found"<<endl;
else
{
for(pos=it->second.begin();pos!=it->second.end();pos++)
cout<<*pos<<endl;
}
break;
}
}
return 0;
}
最后试了一下线性搜索，居然过了，看来时间没卡的很严。。。
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
typedef struct book
{
char id[10];
char title[85];
char author[85];
char keywords[100];
char publisher[85];
char year[10];
}BOOK;
BOOK book_list[10005];
int compare(const void *a,const void *b)
{
BOOK a1 = *(BOOK *)a;
BOOK b1 = *(BOOK *)b;
return strcmp(a1.id,b1.id);
}
void QueryBook(int qnum, char qword[],int nBook)
{
bool found = false;
for(int i=0;i<nBook;i++)
{
BOOK curbook = book_list[i];
switch(qnum)
{
case 1: // title
if(strcmp(qword,curbook.title)==0)
{
printf("%s\n",curbook.id);
found = true;
}
break;
case 2: // author
if(strcmp(qword,curbook.author)==0)
{
printf("%s\n",curbook.id);
found = true;
}
break;
case 3: // keyword
if(strstr(curbook.keywords,qword)!=NULL)
{
printf("%s\n",curbook.id);
found = true;
break;
}
break;
case 4: // publisher
if(strcmp(qword,curbook.publisher)==0)
{
printf("%s\n",curbook.id);
found = true;
}
break;
case 5: // year
if(strcmp(qword,curbook.year)==0)
{
printf("%s\n",curbook.id);
found = true;
}
break;
}
}
if(!found)
printf("Not Found\n");
}
int main()
{
int N,M;
scanf("%d",&N);
for(int i=0;i<N;i++)
{
scanf("%s",book_list[i].id);
getchar();
gets(book_list[i].title);
gets(book_list[i].author);
gets(book_list[i].keywords);
gets(book_list[i].publisher);
scanf("%s",book_list[i].year);
}
qsort(book_list,N,sizeof(BOOK),compare);
scanf("%d",&M);
for(int i=0;i<M;i++)
{
int qnum;
char qword[100];
scanf("%d: ",&qnum);
gets(qword);
printf("%d: %s\n",qnum,qword);
QueryBook(qnum,qword,N);
}
return 0;
}
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