#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define BUFMAX 1005

typedef struct elev {
    char nume[80];
    float media;
} Elev;

void create_binary_file(char file_name[])
{
    FILE* binary_file_stream = fopen(file_name, "wb");
    if(binary_file_stream == NULL) {
        fprintf(stderr, "%s", "failed\n");
    }

    Elev elevi[20];
    int n;
    scanf("%d", &n);
    for(int i = 0; i < n; i++) {
        scanf("%s %f", elevi[i].nume, &elevi[i].media);
    }
    //size_t fwrite ( void * ptr, size_t size, size_t count, FILE * stream );
    fwrite(&n, sizeof(int), 1, binary_file_stream);
    fwrite(elevi, sizeof(Elev), n, binary_file_stream);

    fclose(binary_file_stream);
}

void read_binary_file(char file_name[]) {
    FILE* binary_file_stream = fopen(file_name, "rb");
    if(binary_file_stream == NULL) {
        fprintf(stderr, "%s", "failed\n");
    }
    int n;
    Elev elevi[20];
    fread(&n, sizeof(int), 1, binary_file_stream);
    fread(elevi, sizeof(Elev), n, binary_file_stream);

    for(int i = 0; i < n; i++) {
        printf("%s %f\n", elevi[i].nume, elevi[i].media);
    }
    fclose(binary_file_stream);
}

void positions(char file_name[], int pos[], int* dim)
{
    FILE* binary_file_stream = fopen(file_name, "rb");
    if(binary_file_stream == NULL) {
        fprintf(stderr, "%s", "failed\n");
    }

    int n;
    Elev elevi[20];
    fread(&n, sizeof(int), 1, binary_file_stream);
    fread(elevi, sizeof(Elev), n, binary_file_stream);

    for(int i = 0; i < n; i++) {
        if(elevi[i].media >= 7.50) {
            pos[(*dim)++] = i;
        }
    }
    fclose(binary_file_stream);
}

int main(int argc, char **argv)
{
    create_binary_file("fisier_binar.bin");
    read_binary_file("fisier_binar.bin");

    int vec[20];
    int dim = 0;
    positions((char*)"fisier_binar.bin", vec, &dim);

    FILE* binary_file_stream = fopen("fisier_binar.bin", "rb");
    if(binary_file_stream == NULL) {
        fprintf(stderr, "%s", "failed\n");
    }

    int n;
    char nume[80];
    fread(&n, sizeof(int), 1, binary_file_stream);
    for(int i = 0; i < dim; i++) {
        int pos = vec[i];
        fseek(binary_file_stream, pos * sizeof(Elev) + sizeof(n), SEEK_SET);
        fread(nume, sizeof(char), 20, binary_file_stream);
    }
    return 0;
}