【PAT甲級】Course List for Student

2019 年 11 月 8 日
筆記

本文鏈接：https://blog.csdn.net/weixin_42449444/article/details/89715339

Problem Description：

Zhejiang University has 40000 students and provides 2500 courses. Now given the student name lists of all the courses, you are supposed to output the registered course list for each student who comes for a query.

Input Specification:

Each input file contains one test case. For each case, the first line contains 2 positive integers: N (≤40,000), the number of students who look for their course lists, and K (≤2,500), the total number of courses. Then the student name lists are given for the courses (numbered from 1 to K) in the following format: for each course i, first the course index i and the number of registered students Ni (≤200) are given in a line. Then in the next line, Ni student names are given. A student name consists of 3 capital English letters plus a one-digit number. Finally the last line contains the N names of students who come for a query. All the names and numbers in a line are separated by a space.

Output Specification:

For each test case, print your results in N lines. Each line corresponds to one student, in the following format: first print the student's name, then the total number of registered courses of that student, and finally the indices of the courses in increasing order. The query results must be printed in the same order as input. All the data in a line must be separated by a space, with no extra space at the end of the line.

Sample Input:

11 5  4 7  BOB5 DON2 FRA8 JAY9 KAT3 LOR6 ZOE1  1 4  ANN0 BOB5 JAY9 LOR6  2 7  ANN0 BOB5 FRA8 JAY9 JOE4 KAT3 LOR6  3 1  BOB5  5 9  AMY7 ANN0 BOB5 DON2 FRA8 JAY9 KAT3 LOR6 ZOE1  ZOE1 ANN0 BOB5 JOE4 JAY9 FRA8 DON2 AMY7 KAT3 LOR6 NON9

Sample Output:

ZOE1 2 4 5  ANN0 3 1 2 5  BOB5 5 1 2 3 4 5  JOE4 1 2  JAY9 4 1 2 4 5  FRA8 3 2 4 5  DON2 2 4 5  AMY7 1 5  KAT3 3 2 4 5  LOR6 4 1 2 4 5  NON9 0

解題思路：

我還是比較機智，這題直接把map和vector結合起來用就AC啦。建立一個map<string, vector<int> > m，m的key是學生的姓名，m的value是個int型的vector ，它用來存放該學生所選的所有課程的課程號。輸入完成後無腦sort，然後輸出每個學生的姓名name、學生選擇的課程數m[name].size()，for-each輸出該學生選擇的所有課程的課程號即可。map和vector結合起來用很酷，難道不是嗎？

AC程式碼：

#include <bits/stdc++.h>  using namespace std;    int main()  {      int N,K;  //N個學生、K門課程      cin >> N >> K;      map<string, vector<int> > m;      while(K--)      {          int id,cnt;   //課程號id和選該門課程的學生數cnt          cin >> id >> cnt;          while(cnt--)          {              string name;              cin >> name;              m[name].push_back(id);          }      }      while(N--)      {          string name;          cin >> name;          cout << name << " " << m[name].size();          sort(m[name].begin(), m[name].end());  //升序排列學生選的課程號          for(auto it : m[name])          {              cout << " " << it;          }          cout << endl;      }      return 0;  }