50139. GPA

#include <stdio.h>
#include <stdlib.h>
#include "GPA_calculation.h"

// struct Class{
//     int academic_credit;
//     char score[3];
// };
// struct Student{
//     char name[20];
//     int N_class; // total number of classes the student takes.
//     int N_credit; // total number of academic credits.
//     double GPA;
//     struct Class all_class[10];
// };

int cmp(const void* sa, const void* sb){
    struct Student* a = (struct Student*)sa;
    struct Student* b = (struct Student*)sb;

    if(b->GPA > a->GPA) return 1;
    else if(b->GPA == a->GPA) return 0;
    else return -1;
}


static double mapping[10] = {(double)4.3, (double)4.0, (double)3.7,
                             (double)3.3, (double)3.0, (double)2.7,
                             (double)2.3, (double)2.0, (double)1.7, (double)0.0};

double get_gpa(char* score){
    int p;
    if(score[0] == 'A') p = 1;
    else if(score[0] == 'B') p = 4;
    else if(score[0] == 'C') p = 7;
    else if(score[0] == 'F') p = 9;
    if(score[1] == '+') p--;
    else if(score[1] == '-') p++;
    return mapping[p];
}

void get_cred_gpa(struct Student* s){
    s->N_credit = 0;
    double sum = (double)0.0;
    for(int i = 0; i < s->N_class; i++){
        s->N_credit += s->all_class[i].academic_credit;
        sum += get_gpa(s->all_class[i].score) * (double)(s->all_class[i].academic_credit);
    }
    s->GPA = (double)sum / (double)(s->N_credit);
}

void GPA_calculation(struct Student stnd[], int n){
    int num_awards = ((n - 1) / 20) + 1;
    for(int i = 0; i < n; i++) get_cred_gpa(&stnd[i]);
    qsort(stnd, n, sizeof(struct Student), cmp);

    for(int i = 0; i < num_awards; i++){
        struct Student* s = &stnd[i];
        if(s->N_credit < 15 || s->GPA < (double)(3.38)) continue;
        printf("%d %s %f\n", i + 1, s->name, s->GPA);
    }

}