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

struct sll_node
{
    int data;
    struct sll_node *next;
};
bool insert_before(struct sll_node **node, int data)
{
    struct sll_node *new_node = (struct sll_node *)malloc(sizeof(struct sll_node));
    if(NULL!=new_node){
        new_node->data = data;
        new_node->next = *node;
        * node = new_node;
        return true;
    }
    return false;
}
bool  insert_back(struct sll_node **node, int data)
{
    *node = (struct sll_node *)malloc(sizeof(struct sll_node));
    if(NULL!= *node){
        (*node)->data = data;
        (*node)->next = NULL;
        return true;
    }
    return false;
}
bool insert_node(struct sll_node **node, int data)
{
    if(NULL!= *node){
        if((*node)->data<=data)
            return insert_before(node, data);
        else
            return insert_node (&(*node)->next, data );
    }
    else
        return insert_back(node, data);
}
void delete_node(struct sll_node **node, int data)
{
    if(NULL!= *node){
        if((*node)->data == data){
                struct sll_node *next = (*node)->next;
                free(*node);
                *node = next;
        }
        else
            delete_node(&(*node)->next, data);
    }
}
void print_list(struct sll_node *node)
{
    if(NULL!=node){
        printf(" %d ", node->data);
        print_list(node->next);
    }
    else
        printf("\n");
}
void print_list_backwards(struct sll_node *node)
{
    if(NULL!=node){
        print_list_backwards(node->next);
        printf(" %d ", node->data);

    }
}
void remove_list(struct sll_node **node)
{
    if(NULL!= *node){
        remove_list(&(*node)->next);
        free(*node);
    }
}
void usun(struct sll_node **node)
{

    if(NULL!= *node){
        if(NULL!= (*node)->next){
        if((*node)->data == (*node)->next->data){
            usun(&(*node)->next);
        }
        else{
            struct sll_node *tmp = (*node)->next;
            delete_node(node, (*node)->data);
            *node = tmp;
            usun(&(*node)->next);

    }
    }
    else {
        delete_node(node, (*node)->next);
    }

    }
}

int main()
{
    struct sll_node *front = NULL;
    int i;
    for(i=1; i<5; i++)
        if(! insert_node (&front, i))
            fprintf(stderr, " Blad dodawania elementu do listy!\n");
    for(i=6; i<10; i++)
        if(! insert_node (&front, i))
            fprintf(stderr, " Blad dodawania elementu do listy!\n");
    print_list(front);
    printf("\n");

    if(! insert_node(&front, 5))
        fprintf (stderr , " Blad dodawania elementu do listy!\n");
    if(! insert_node(&front, 7))
        fprintf (stderr , " Blad dodawania elementu do listy!\n");
    print_list(front);

    usun(&front);
    puts("");
    print_list(front);

    remove_list(&front);
    front = NULL;
    return 0;
}