1039. Course List for Student (25)

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 (<=40000), the number of students who look for their course lists, and K (<=2500), 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 N_i (<= 200) are given in a line. Then in the next line, N_i 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 54 7BOB5 DON2 FRA8 JAY9 KAT3 LOR6 ZOE11 4ANN0 BOB5 JAY9 LOR62 7ANN0 BOB5 FRA8 JAY9 JOE4 KAT3 LOR63 1BOB55 9AMY7 ANN0 BOB5 DON2 FRA8 JAY9 KAT3 LOR6 ZOE1ZOE1 ANN0 BOB5 JOE4 JAY9 FRA8 DON2 AMY7 KAT3 LOR6 NON9

Sample Output:

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

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给出各门课有哪些学生选择了，要求输出各个学生选了哪些课。一开始是直接用map，以学生姓名为键值，储存学生选择了哪些课，输出的时候直接查找就可以，结果最后一个例子超时。观察学生的姓名，都是四位，前三位是大写字母，第四位是数字，所以可以映射成一个整数，这样就能得到键值，进行保存信息和读取信息。

代码：

#include <iostream>#include <cstring>#include <vector>#include <cstdlib>#include <cstdio>#include <map>#include <algorithm>using namespace std;int Hash(char s[]){return (s[0]-'A')*26*26*10+(s[1]-'A')*26*10+(s[2]-'A')*10+(s[3]-'0');}int main(){int n,k;scanf("%d %d",&n,&k);vector<int>stu[26*26*26*10+1];for(int i=0;i<k;i++){int course,m;scanf("%d %d",&course,&m);for(int j=0;j<m;j++){char *name=new char[4];scanf("%s",name);int key=Hash(name);stu[key].push_back(course);}}for(int i=0;i<n;i++){char name[4];scanf("%s",name);int key=Hash(name);vector<int>res=stu[key];printf("%s %d",name,res.size());sort(res.begin(),res.end());for(int j=0;j<res.size();j++){printf(" %d",res[j]);}printf("\n");}}