zad3.c

#include <stdio.h>
#include <stdlib.h>
typedef struct node_tag{
    int x;
    struct node_tag* next;
}node;

node* addNode(node* list, int x){    
    list->next = (node*) malloc(sizeof(node));   
    list->next->next = NULL;
    list->x = x;
    return list->next;
}

int existOnList(node* list, int value){
    node* n = list;
    while(n->next!= NULL){
        if(n->x == value){
            return 1;
        }        
        n = n->next;
    }
    return 0;
}

void printList(node* list, node* secList){
    node* n = list;
    while(n->next!= NULL){
        if (!existOnList(secList,n->x))
        {
            printf("%d\n", n->x);
        }
        
        n = n->next;
    }
}

node* createNumberList(FILE* f){
    node* list = (node*) malloc(sizeof(node));
    node* head = list;
    int value = 0;
    while (fscanf(f, "%d", &value) != EOF){
        
        list = addNode(list, value);
    }

    return head;
}
int main(void) {    
    FILE* aFile = fopen("a.txt", "r");
    FILE* bFile = fopen("b.txt", "r");
    node* alist = (node*) createNumberList(aFile);
    node* blist = (node*) createNumberList(bFile);
    printList(alist, blist);
    
    return 0;
}