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

typedef struct {
  int info;
} DATA;

typedef struct node {
  DATA data;
  struct node* next;
} NODE;

void init(NODE** head) {
  *head = NULL;
}

void print_list(NODE* head) {
  NODE * temp;
  for (temp = head; temp; temp = temp->next)
    printf("%5d", temp->data.info);
  printf("\n");
}

NODE* add(NODE* node, DATA data) {
  NODE* temp = (NODE*) malloc(sizeof (NODE));
  if (temp == NULL) {
    exit(0); // no memory available
  }
  temp->data = data;
  temp->next = node;
  node = temp;
  return node;
}

void add_at(NODE* node, DATA data) {
  NODE* temp = (NODE*) malloc(sizeof (NODE));
  if (temp == NULL) {
    exit(EXIT_FAILURE); // no memory available
  }
  temp->data = data;
  temp->next = node->next;
  node->next = temp;
}

void remove_node(NODE* head) {
  NODE* temp = (NODE*) malloc(sizeof (NODE));
  if (temp == NULL) {
    exit(EXIT_FAILURE); // no memory available
  }
  temp = head->next;
  head->next = head->next->next;
  free(temp);
}

NODE * reverse_rec(NODE * ptr, NODE * previous) {
  NODE * temp;
  if (ptr->next == NULL) {
    ptr->next = previous;
    return ptr;
  } else {
    temp = reverse_rec(ptr->next, ptr);
    ptr->next = previous;
    return temp;
  }
}

NODE * reverse(NODE * node) {
  NODE * temp;
  NODE * previous = NULL;
  while (node != NULL) {
    temp = node->next;
    node->next = previous;
    previous = node;
    node = temp;
  }
  return previous;
}

NODE *free_list(NODE *head) {
  NODE *tmpPtr = head;
  NODE *followPtr;
  while (tmpPtr != NULL) {
    followPtr = tmpPtr;
    tmpPtr = tmpPtr->next;
    free(followPtr);
  }
  return NULL;
}

NODE *sort_list(NODE *head) {
  NODE *tmpPtr = head, *tmpNxt = head->next;
  DATA tmp;
  while (tmpNxt != NULL) {
    while (tmpNxt != tmpPtr) {
      if (tmpNxt->data.info < tmpPtr->data.info) {
	tmp = tmpPtr->data;
	tmpPtr->data = tmpNxt->data;
	tmpNxt->data = tmp;
      }
      tmpPtr = tmpPtr->next;
    }
    tmpPtr = head;
    tmpNxt = tmpNxt->next;
  }
  return tmpPtr;
}

int main() {

  int i;
  NODE* head;
  NODE* node;
  DATA element;
  printf("Add Elements to List:\n");
  init(&head);
  for (i = 53; i <= 63; i++) {
    if (i == 60) {
      element.info = 27;
    }
    else {
      element.info = i;
    }	  
    printf("Add Element %2d To The List.\n", element.info);
    head = add(head, element);
  }
  printf("\nPrint The List:\n");
  print_list(head);

  printf("\nRemove An Element From The List:\n");
  node = head->next->next->next->next;
  remove_node(node);
  print_list(head);

  printf("\nAdd An Element To The List:\n");
  node = head->next->next->next;
  element.info = 2000;
  add_at(node, element);
  print_list(head);

  printf("\nReverse The list:\n");
  head = reverse(head); // Revers The List
  print_list(head);
  
  printf("\nSort The list:\n");
  head = sort_list(head); // Sort The List
  print_list(head);

  // free the list
  //
  head = free_list(head);

  return (EXIT_SUCCESS);
}