/*
** $Id: lists.c 789 2008-02-23 06:27:49Z phf $
**
** Linked list code from Spring 2008. Sorry, very few
** comments, please ask if you don't get something.
*/

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

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

struct node *head = NULL;

void insert(int x)
{
  struct node *node = malloc(sizeof(struct node));
  node->next = head;
  node->data = x;
  head = node;
}

struct node *find(int x, struct node **prev) // horrible :-)
{
  struct node *node = head;
  struct node *nprv = NULL;
  while (node != NULL && node->data != x) {
    nprv = node;
    node = node->next;
  }
  *prev = nprv; // fake 2nd result
  return node;
}

void rem(int x)
{
  struct node *prev;
  struct node *node = find(x, &prev);
  if (node != NULL) {
    if (prev != NULL) {
      prev->next = node->next;
    }
    else { // prev == NULL
      head = node->next;
    }
    free(node);
  }
}

void print(void)
{
  for (struct node *node = head; node != NULL; node = node->next) {
    printf("node at %p has data %d\n", node, node->data);
  }
  puts("--------");
}

int main()
{
  print();
  // head: --|

  // insert 7
  insert(7);

  print();
  // head: -->[7]--|

  // insert 12
  insert(12);
  
  print();
  // head: -->[12]-->[7]--|

  insert(1);
  print();
  insert(36);
  print();
  // head: -->[36]-->[1]-->[12]-->[7]--|

  rem(4);
  print();
  rem(1);
  print();
  rem(36);
  print();
  rem(7);
  print();
  rem(12);
  print();


  return EXIT_SUCCESS;
}