// linkedlist.h: header file,  ref in
//   linkedlist.c, stack.c, queue.c
void addlast(int );
void addfirst(int );
int removefirst();
void printlist();
void printreverse();
int empty();
// linkedlist.c:
#include <stdio.h>
#include <stdlib.h>
#include "linkedlist.h"

struct listnode {
   int data;
   struct listnode* next;
};

static void printreverse0(struct listnode* );

struct listnode* first = NULL; // front, top
struct listnode* last = NULL;  // rear

void addlast(int dataitem) {
   // or add to rear, i.e. enqueue
   // (a). Supply code for this function.
   // Add a new link at "last" end
   //   holding "dataItem".
   // May need to treat empty list
   //   as a separate case.
}

void addfirst(int dataitem) {
   // or add to front, i.e. dequeue, or push
   // (b). Supply code for this function.
   // Add a new link at "first" end
   //   holding "dataItem".
}

int removefirst() {
   // or pop
   // (c). Supply code for this function.
   // Must remove link at "first" end,
   //   and return data value stored there.
}

int empty() {
   return first == NULL;
}

void printlist() {
   // first to last, or front to rear
   // (d). Supply code to print the list
   //   from first to last.
}

void printreverse() {
   printreverse0(first);
   printf("\n");
}

static void printreverse0(struct listnode* temp){
   // last to first, or rear to front
   // (e). Supply code for a RECURSIVE function
   //   that prints from last to first.
   }
}

int delete(int dataItem) {
   // delete from anywhere in list
   // (f). Supply code for a function that
   //   will delete "dataItem" if it is present.
   //   return 0 if item was deleted.
   //   return -1 if item was not present.
}

// stack.h: header file,
void push(int );
int pop();
// stack.c: based on linkedlist.c
#include "linkedlist.h"
#include "stack.h"
void push(int dataItem) {
   addfirst(dataItem);
}
int pop() {
   return removefirst();
}
// queue.h: header file
void enqueue(int );
int dequeue();
// queue.c: based on linkedlist.c
#include "linkedlist.h"
#include "queue.h"
void enqueue(int dataitem) {
   addlast(dataitem);
}
int dequeue() {
   return removefirst();
}
// linkedlist.h: header file
void printlist();
void printreverse();
int empty();
// linktest.c: test program.  Note:
//  can't use both stack and queue
#include <stdio.h>
#include "queue.h"
#include "stack.h"
#include "linkedlist0.h"

void main() {
   int a[] = {2, 3, 5, 7, 11, 13};
   int i, t;
   for (i = 0; i < 6; i++)
      enqueue(a[i]);
   printf("Queue:");
   printlist();
   printreverse();
   t = dequeue(); printf("%i ", t);
   t = dequeue(); printf("%i\n", t);
   // must empty queue to use stack
   while (!empty()) t = dequeue();

   for (i = 0; i < 6; i++)
      push(a[i]);
   printf("Stack:");
   printlist();
   printreverse();
   t = pop(); printf("%i ", t);
   t = pop(); printf("%i\n", t);
   push(11);
   push(13);
   
   printf("Delete test:\n");
   printlist();
   for (i = 5; i >= 0; i--) {
      delete(a[i]);
      printlist();
   }
   printf("2nd Delete test:\n");
   for (i = 0; i < 6; i++)
      push(a[i]);
   printlist();
   printf("%i ", delete(1));
   printf("%i ", delete(8));
   printf("%i\n", delete(15));
   printf("3rd Delete test:\n");
   for (i = 0; i < 6; i++) {
      delete(a[i]);
      printlist();
   }
}

Queue:
2 3 5 7 11 13 
13 11 7 5 3 2 
2 3
Stack:
13 11 7 5 3 2 
2 3 5 7 11 13
13 11
Delete test:
13 11 7 5 3 2 
11 7 5 3 2 
7 5 3 2 
5 3 2 
3 2 
2 

Empty
2nd Delete test:
13 11 7 5 3 2 
-1 -1 -1
3rd Delete test:
13 11 7 5 3 
13 11 7 5 
13 11 7 
13 11 
13 
Empty