很简单的题，就是考察一个map的使用，不过这题有个陷阱就是最后输出的id必须是7位的，我做这题的时候用到了string的分割，其实不需要，直接用getchar()就可以判断结束条件，注意使用getline时要吃掉\n
#include<string>
#include<cstdlib>
#include<vector>
#include<stack>
#include<queue>
#include<utility>
#include<map>
#include<set>
#include<cstdlib>
#include<string.h>
#include<stdio.h>
#include<algorithm>
#include<functional>
#include<iostream>
#define INF 0x6ffff
using namespace std;map<string, set<int>> title;
map<string, set<int>> author;
map<string, set<int>> keyword;
map<string, set<int>> publisher;
map<string, set<int>> year;vector<string> split(const string &str, const string &pattern)
{//const char* convert to char*char * strc = new char[strlen(str.c_str()) + 1];strcpy(strc, str.c_str());vector<string> resultVec;char* tmpStr = strtok(strc, pattern.c_str());while (tmpStr != NULL){resultVec.push_back(string(tmpStr));tmpStr = strtok(NULL, pattern.c_str());}delete[] strc;return resultVec;
}void print(set<int> &res) {if (res.empty())cout << "Not Found" << endl;else {for (auto x : res)printf("%07d\n", x);}
}int main() {int n,m;cin >> n;while (n--) {int id;string t, a, k, p,y;cin >> id;cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');getline(cin, t);getline(cin, a);getline(cin, k);getline(cin, p);cin >> y;vector<string> key = split(k, " ");for (auto x : key)keyword[x].insert(id);title[t].insert(id);author[a].insert(id);publisher[p].insert(id);year[y].insert(id);}cin >> m;cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');while (m--) {int num;scanf("%d: ", &num);string query;getline(cin, query);cout << num << ": " << query << endl;switch (num) {case 1:print(title[query]); break;case 2:print(author[query]); break;case 3:print(keyword[query]); break;case 4:print(publisher[query]); break;case 5:print(year[query]); break;}}return 0;
}网上的代码，其中对一行字符串分别以空格进行分割，最后用\n进行判断的处理可以学习一下：
#include <iostream>
#include <map>
#include <set>
using namespace std;
map<string, set<int> > title, author, key, pub, year;
void query(map<string, set<int> > &m, string &str) {if(m.find(str) != m.end()) {for(auto it = m[str].begin(); it != m[str].end(); it++)printf("%07d\n", *it);} elsecout << "Not Found\n";
}
int main() {int n, m, id, num;scanf("%d", &n);string ttitle, tauthor, tkey, tpub, tyear;for(int i = 0; i < n; i++) {scanf("%d\n", &id);getline(cin, ttitle);title[ttitle].insert(id);getline(cin, tauthor);author[tauthor].insert(id);while(cin >> tkey) { //这里可以学习一下key[tkey].insert(id);char c = getchar();if(c == '\n') break;}getline(cin, tpub);pub[tpub].insert(id);getline(cin, tyear);year[tyear].insert(id);}scanf("%d", &m);for(int i = 0; i < m; i++) {scanf("%d: ", &num);string temp;getline(cin, temp);cout << num << ": " << temp << "\n";if(num == 1) query(title, temp);else if(num == 2) query(author, temp);else if(num == 3) query(key, temp);else if(num == 4) query(pub,temp);else if(num ==5) query(year, temp);}return 0;
}