Kolokwium2_Lista_Dwukierunkowa_Cykliczna

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

struct list_node{
    int data;
    struct list_node *previous, *next;
};

struct list_node *create_list(int data)
{
    struct list_node *first_node = (struct list_node*)malloc(sizeof(struct list_node));
    if(first_node){
        first_node->data = data;
        first_node->previous = first_node->next = first_node;
    }
    return first_node;
}

struct list_node *find_minimum_value_node(struct list_node *list_pointer)
{
    struct list_node *start, *result;
    start = result = list_pointer;
    int minimum = list_pointer->data;
    do{
        if(minimum > list_pointer->data){
            minimum = list_pointer->data;
            result = list_pointer;
        }
        list_pointer = list_pointer->next;
    }while(start != list_pointer);
    return result;
}

struct list_node *find_next_node(struct list_node *list_pointer, int data)
{
    list_pointer = find_minimum_value_node(list_pointer);
    struct list_node *start = list_pointer;
    do{
        if(list_pointer->data > data)
            break;
        list_pointer = list_pointer->next;
    }while(start != list_pointer);
    return list_pointer;
}

void add_node(struct list_node *list_pointer, int data)
{
    if(list_pointer){
        struct list_node *new_node = (struct list_node*)malloc(sizeof(struct list_node));
        if(new_node){
            new_node->data = data;
            list_pointer = find_next_node(list_pointer, data);

            new_node->next = list_pointer;
            new_node->previous = list_pointer->previous;
            list_pointer->previous->next = new_node;
            list_pointer->previous = new_node;
        }
    }
}

struct list_node *delete_node(struct list_node *list_pointer, int data)
{
    if(list_pointer){
        list_pointer = find_next_node(list_pointer, data);
        list_pointer = list_pointer->previous;
        if(list_pointer->data == data){
            if(list_pointer == list_pointer->next){
                free(list_pointer);
                return NULL;
            }
            struct list_node *next_node = list_pointer->next;
            list_pointer->previous->next = list_pointer->next;
            list_pointer->next->previous = list_pointer->previous;
            free(list_pointer);
            list_pointer = next_node;
        }
        else
            fprintf(stderr, "Brak elementu w liscie!\n");
    }
    return list_pointer;
}

void print_list(struct list_node *list_pointer)
{
    if(list_pointer){
        list_pointer = find_minimum_value_node(list_pointer);
        struct list_node *start = list_pointer;
        do{
            printf("%d ", list_pointer->data);
            list_pointer = list_pointer->next;
        }while(start != list_pointer);
    }
    else
        fprintf(stderr, "Lista jest pusta!\n");
    printf("\n");
}

void remove_list(struct list_node **list_pointer)
{
    if(*list_pointer){
        struct list_node *start = *list_pointer;
        do{
            struct list_node *next_node = (*list_pointer)->next;
            free(*list_pointer);
            *list_pointer = next_node;
        }while(start != (*list_pointer));
        *list_pointer = NULL;
    }
    else
        fprintf(stderr, "Lista jest pusta!\n");
}

int main(void)
{
    srand(time(NULL));

    struct list_node *list_pointer = (struct list_node*)malloc(sizeof(struct list_node));
    list_pointer = create_list(10);

    int i;
    for(i = 0; i < 10; i++)
        add_node(list_pointer, rand()%10);
    print_list(list_pointer);

    list_pointer = delete_node(list_pointer, 10);
    print_list(list_pointer);

    remove_list(&list_pointer);
    return 0;
}