pvjc24/cv10/program.c

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

struct students* reading();
struct students* sort_students(struct students* );

struct students{
    char* name;
    struct students* next_student;
};
int main()
{
    int quantity;
    char qty_buffer[10];
    fgets(qty_buffer, sizeof(qty_buffer), stdin);
    quantity = atoi(qty_buffer);
    if(quantity<=0){
        puts("Nespravny vstup");
        return 0;
    }
    struct students* readed = reading();
    if(readed==NULL){
        puts("Ziadne prihlasky");
        return 0;
    }
    struct students* sorted = sort_students(readed);
    struct students* next_element=sorted;
    int counter=0;
    puts("Prijati studenti:");
    while(next_element!=NULL){
        if(counter==quantity){
            puts("Neprijati studenti:");
        }
        counter++;
        printf("%s",next_element->name);
        next_element=next_element->next_student;
    }
    return 0;
}

struct students* reading(){
    char buffer[100];
    struct students* first_student =malloc(sizeof(struct students));
    struct students* current_student=first_student;
    struct students* last=NULL;
    while(fgets(buffer, sizeof(buffer), stdin )){
            if(strlen(buffer)==1){
                break;
            }
        current_student->name=malloc(strlen(buffer) + 1);
        strcpy(current_student->name, buffer);
        current_student->next_student=malloc(sizeof(struct students));
        last=current_student;
        current_student=current_student->next_student;
    }
    free(current_student);
    if(last==NULL){
        return NULL;
    }
    last->next_student=NULL;

    return first_student;
}


//A - B - C
//A - C
//A - C - B

//A - C - B - D - F
//B->next_student  C
//B
struct students* sort_students(struct students* list_of_students_to_sort){
    struct students* current_link=list_of_students_to_sort;
    struct students* previous_element=NULL;
    struct students* first_element=list_of_students_to_sort;
    struct students* A;
    struct students* B;
    struct students* C;
    struct students* D;
    int counter=1;
    while (counter!=0){
        counter=0;
        current_link=first_element;
        previous_element=NULL;
        while (current_link->next_student!=NULL){
            A=previous_element;
            B=current_link;
            C=current_link->next_student;
            D=current_link->next_student->next_student;
            if(strcmp(B->name, C->name)==0){
                counter++;
                B->next_student=D;
                free(C->name);
                free(C);
                break;
            }
            if(strcmp(B->name, C->name)>0){
                counter++;
                if(A!=NULL){
                    A->next_student=C;
                }else{
                   first_element=C;
                }
                B->next_student=D;
                C->next_student=B;
                break;
            }
            previous_element = current_link;
            current_link=current_link->next_student;
        }
    }

    return first_element;
}