PAT 1047 Student List for Course(哈希)

学生选课系统：课程注册与学生名单输出

最新推荐文章于 2024-09-17 13:15:00 发布

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本文介绍了一个学生选课系统的实现方法，系统能够处理4万名学生的选课信息，包括2500门课程的注册情况。通过哈希表优化学生姓名查找，实现了高效的学生名单输出功能，对于每门课程，系统能够输出注册该课程的所有学生名单。

Zhejiang University has 40,000 students and provides 2,500 courses. Now given the registered course list of each student, you are supposed to output the student name lists of all the courses.

Input Specification:

Each input file contains one test case. For each case, the first line contains 2 numbers: N (≤40,000), the total number of students, and K (≤2,500), the total number of courses. Then N lines follow, each contains a student's name (3 capital English letters plus a one-digit number), a positive number C (≤20) which is the number of courses that this student has registered, and then followed by C course numbers. For the sake of simplicity, the courses are numbered from 1 to K.

Output Specification:

For each test case, print the student name lists of all the courses in increasing order of the course numbers. For each course, first print in one line the course number and the number of registered students, separated by a space. Then output the students' names in alphabetical order. Each name occupies a line.

Sample Input:

10 5
ZOE1 2 4 5
ANN0 3 5 2 1
BOB5 5 3 4 2 1 5
JOE4 1 2
JAY9 4 1 2 5 4
FRA8 3 4 2 5
DON2 2 4 5
AMY7 1 5
KAT3 3 5 4 2
LOR6 4 2 4 1 5

Sample Output:

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

思路:课程名哈希

代码

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
const int Max=26*26*26*10+5;
vector<int> v[2505];
char Name[Max][5];
int Hash(char *str)
{
    int Sum=0;
    for(int i=0;i<3;i++)
    {
        Sum=Sum*26+str[i]-'A';
    }
    Sum=Sum*10+str[3]-'0';
    return Sum;
}
int main()
{
    int N,K,x,Num;
    scanf("%d %d",&N,&K);
    char str[5];
    while(N--)
    {
        scanf("%s %d",str,&Num);
        int Temp=Hash(str);
        strcpy(Name[Temp],str);
        for(int i=0;i<Num;i++)
        {
            scanf("%d",&x);
            v[x].push_back(Temp);
        }
    }
    for(int i=1;i<=K;i++)
    {
        sort(v[i].begin(),v[i].end());
        int Len=v[i].size();
        printf("%d %d\n",i,Len);
        for(int index=0;index<Len;index++)
             printf("%s\n",Name[v[i][index]]);
    }
    return 0;
}