ListaDwukierunkowa

#include <stdio.h>
#include <malloc.h>

struct element{
    struct element* previous;
    struct element* next;
    int number;
} *first = NULL;

void print(struct element* input){
    if(input != NULL){
        printf("%d ", input->number);
        if(input->next != NULL){
            print(input->next);
        }
        else {
            printf("\n");
        }
    }
    else {
        printf("LISTA JEST PUSTA! \n");
    }
}

void insert(int inputValue, struct element* inputElement, struct element* previous){
    struct element* newfirst = (struct element *)malloc(sizeof(struct element));
    if(inputElement == NULL){
        // pusta lista lub koniec
        struct element* tmp = (struct element *)malloc(sizeof(struct element));
        tmp->previous = previous;
        tmp->next = NULL;
        tmp->number = inputValue;
        if(inputElement == first){
            first = tmp;
        }
        else {
            tmp->previous->next = tmp;
        }
    }
    else {
        if(inputElement->number >= inputValue){
            /* Znaleziony wiekszy - wstawiamy przed nim */
            struct element* tmp = (struct element *)malloc(sizeof(struct element));
            tmp->previous = previous;
            tmp->next = inputElement;
            tmp->number = inputValue;
            if(tmp->previous != NULL){
                tmp->previous->next = tmp;
            }
            else {
                first = tmp;
            }
            tmp->next->previous = tmp;
        }
        else {
            /* Pudlo - szukamy dalej */
            insert(inputValue, inputElement->next, inputElement);
        }
    }
}

void usun(int inputValue){
    if(first == NULL){
        return;
    }
    struct element* tmp = first;
    while(tmp->number != inputValue){
        if(tmp->next == NULL){
            return;
        }
        tmp = tmp->next;
    }
    if(tmp->number == inputValue){
        /* trafienie */
        if(tmp == first){
            if(tmp->next == NULL){
                first = NULL;
            }
            else {
                first = tmp->next;
            }
        }
        else {
            if(tmp->next != NULL){
                tmp->next->previous = tmp->previous;
            }
            if(tmp->previous != NULL){
                tmp->previous->next = tmp->next;
            }
        }
        free(tmp);
    }
}

int main(){
    int option;
    int value;
    int run = 1;
    while(run){
        printf("Wybierz opcje: 1 - insert, 2 - delete, 3 - wyswietl");
        scanf("%d", &option);
        if(option == 1){
            printf("Podaj wartosc do wstawienia: ");
            scanf("%d", &value);
            insert(value, first, NULL);
        }
        else if(option == 2){
            printf("Podaj wartosc do usuniecia: ");
            scanf("%d", &value);
            usun(value);
        }
        else if(option == 3){
            printf("Zawartosc listy ");
            print(first);
        }
        else {
            run = 0;
        }
    }
    return 0;
}