紫书章五习题八 图书管理系统

题意：先输入若干图书的标题和作者，然后按照先按作者名字的字典序排，然后按照书的字典序来排。然后会有三种操作borrow 表示借书 return表示还书，shelve表示让你输出怎么放书（还是按照原来的顺序）

Sample Input"The Canterbury Tales" by Chaucer, G."Algorithms" by Sedgewick, R."The C Programming Language" by Kernighan, B. and Ritchie, D.ENDBORROW "Algorithms"BORROW "The C Programming Language"RETURN "Algorithms"RETURN "The C Programming Language"SHELVEENDSample OutputPut "The C Programming Language" after "The Canterbury Tales"Put "Algorithms" after "The C Programming Language"END

然后学到了
string s;
s.find(“by”);//表示返回b下标；；如果没有找到的话，返回的是string::npos
然后是set里的删除操作
set t;
set :: iterator it;
it= t.find(s);
t.erase(it);
然后一定不要忘了 放在first的情况

#include <iostream>#include <cstring>#include <cstdio>#include <algorithm>#include <cmath>#include <vector>#include <set>#include <map>using namespace std;struct node{    string book;    string au;    node (string a,string b)    {        book=a;        au=b;    }};vector <node> v;//放作者和书名struct lala{    int num;    string book;};lala la[100005];//放还书的书在原来的序号和书名bool cmp(node a,node b){    if(a.au!=b.au)        return a.au<b.au;    else return a.book<b.book;}bool cmp1(lala a2,lala b2){    return a2.num<b2.num;}int main(){   // freopen("E:\\input.txt","r",stdin);    string str;    while(getline(cin,str))    {        if(str=="END")//不能用strcmp            break;        int k=str.find("by");        string book=str.substr(0,k-1);        string au=str.substr(k+3);        v.push_back((node){book,au});    }    sort(v.begin(),v.end(),cmp);    int h=0;    set< string > br1;     set<string> :: iterator it;     string str1;    while(getline(cin,str1))    {        if(str1=="END")            break;        string book;        if(str1.length()>6)               book=str1.substr(7);        if(str1[0]=='B')        {            br1.insert(book);        }        else if(str1[0]=='R')        {            lala temp;            for(int i=0;i<v.size();i++)            {                node t=v[i];                if(t.book==book)                {                    temp.book=book;                    temp.num=i;                    break;                }            }            la[h++]=temp;          //  cout<<h<<endl;        }        else if(str1[0]=='S')        {            sort(la,la+h,cmp1);            for(int i=0;i<h;i++)            {                int j;                if(la[i].num==0) cout<<"Put "<<la[i].book<<" first\n";                else{                    for(j=la[i].num;j>=0;j--)                    {                        if(j<0) break;                        if(br1.count(v[j].book)==0)                        {                            cout<<"Put "<<la[i].book<<" after ";                            cout<<v[j].book<<endl;                            break;                        }                    }                    if(j<0) cout<<"Put "<<la[i].book<<" first\n";//这个要注意                }                   it=br1.find(la[i].book);                   br1.erase(it);            }             cout<<"END\n";           //  memset(la,0,sizeof(la));             h=0;        }    }    return 0;}