void pre_order_travelse(btree_node* root)
{
 if(root != NULL)
 {
  printf("%c-", ((struct node*)root)->v);
  pre_order_travelse(root->left);
  pre_order_travelse(root->right);
 }
}

void mid_order_travelse(btree_node* root)
{
 if(root != NULL)
 {
  mid_order_travelse(root->left);
 
  printf("%c-", ((struct node*)root)->v);
 
  mid_order_travelse(root->right);
 }
}

void post_order_travelse(btree_node* root)
{
 if(root != NULL)
 {
  post_order_travelse(root->left);
 
  post_order_travelse(root->right);
 
  printf("%c-", ((struct node*)root)->v);
 
 
 }
}

void level_order_travelse(btree_node* root)
{
 
 if(root != NULL)
 {
  LinkQueue* queue = LinkQueue_Create();
 
  if(queue != NULL)
  {
   
   LinkQueue_Append(queue, root);
   
   while( LinkQueue_Length(queue) > 0)
   {
    struct node* node = (struct node*)LinkQueue_Retrieve(queue);
   
    printf("%c, ", node->v);
   
    LinkQueue_Append(queue, node->header.left);
    LinkQueue_Append(queue, node->header.right);
   
   }
 
  }
 
  LinkQueue_Destroy(queue);
 }

}