PAT (A) 1012 The Best Rank

1.问题

1012 The Best Rank(25分)

To evaluate the performance of our first year CS majored students, we consider their grades of three courses only:C- C Programming Language,M- Mathematics (Calculus or Linear Algrbra), andE- English. At the mean time, we encourage students by emphasizing on their best ranks -- that is, among the four ranks with respect to the three courses and the average grade, we print the best rank for each student.

For example, The grades ofC,M,EandA- Average of 4 students are given as the following:

StudentID  C  M  E  A
310101     98 85 88 90
310102     70 95 88 84
310103     82 87 94 88
310104     91 91 91 91

Then the best ranks for all the students are No.1 since the 1st one has done the best in C Programming Language, while the 2nd one in Mathematics, the 3rd one in English, and the last one in average.

Input Specification:

Each input file contains one test case. Each case starts with a line containing 2 numbersNandM(≤2000), which are the total number of students, and the number of students who would check their ranks, respectively. ThenNlines follow, each contains a student ID which is a string of 6 digits, followed by the three integer grades (in the range of [0, 100]) of that student in the order ofC,MandE. Then there areMlines, each containing a student ID.

Output Specification:

For each of theMstudents, print in one line the best rank for him/her, and the symbol of the corresponding rank, separated by a space.

The priorities of the ranking methods are ordered asA>C>M>E. Hence if there are two or more ways for a student to obtain the same best rank, output the one with the highest priority.

If a student is not on the grading list, simply outputN/A.

Sample Input:

5 6
310101 98 85 88
310102 70 95 88
310103 82 87 94
310104 91 91 91
310105 85 90 90
310101
310102
310103
310104
310105
999999

Sample Output:

1 C
1 M
1 E
1 A
3 A
N/A

2.代码

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cmath>

using namespace std;

const int N = 2010;

const int M = 1000000;

struct student{
    int id;
    int grade[4];
}stu[N];

int Rank[M][4];
int now;

char course[4] = {'A', 'C', 'M', 'E'};

bool cmp(student a, student b)
{
    return a.grade[now] > b.grade[now];
}

int main()
{
    //freopen("test.txt","r",stdin);
    
    int n, m;
    
    scanf("%d %d", &n, &m);
    for (int i = 0; i < n; i ++)
    {
        scanf("%d %d %d %d", &stu[i].id, &stu[i].grade[1], &stu[i].grade[2], &stu[i].grade[3]);
        stu[i].grade[0] = round((stu[i].grade[1] + stu[i].grade[2] + stu[i].grade[3]) / 3 + 0.5);    
    }
    
    for (now = 0; now < 4; now ++)
    {
        sort(stu, stu + n, cmp);
        
        Rank[stu[0].id][now] = 1;
        for (int i = 1; i < n; i ++)
            if(stu[i].grade[now] == stu[i - 1].grade[now]) 
                Rank[stu[i].id][now] = Rank[stu[i - 1].id][now];
            else Rank[stu[i].id][now] = i + 1;
    }
    
    int query;
    for (int i = 0; i < m; i ++)
    {
        scanf("%d", &query);
        if(Rank[query][0] == 0)
            printf("N/A\n");
        else
        {    int k = 0;
            for (int j = 0;  j < 4; j ++)
            {
                if(Rank[query][j] < Rank[query][k])
                    k = j;
            }
            
            printf("%d %c\n", Rank[query][k], course[k]);
        }
    }
    return 0;
}

3.总结

• (1) 出现的问题：

  • 刚开始将分数分别定义在结构体中，在之后对分数进行排序时，无法通过循环将功能相同但变量无法统一的一段代码实现。
  • 当名次相同时，需要按照 A > C > M > E 进行输出。

• (2)解决：

  • 使用数组来表示4个不同科目的分数，进行排序时，可以使用一个变量来对不同学生的不同成绩进行排序。
  • 定义一个优先级字符数组，按照此优先级进行输出。