correction

Chains_across_the_Island/Fundamentals/double/double.c

@@ -32,6 +32,7 @@ int dlist_insert(struct dlist **l, size_t index, int e)
         new_node->prev = NULL;
         new_node->next = *l;
         new_node->data = e;
+        new_node->next->prev = new_node;
 
         //dlist_append(*l, e);
         return 0;
@@ -58,19 +59,18 @@ int dlist_insert(struct dlist **l, size_t index, int e)
 
     return 0;
 
-
 }
 
 struct dlist *dlist_delete_at(struct dlist **l, size_t index)
 {
     if(!l || *l) return NULL;
 
-
     struct dlist *old = *l;
     if(index == 0){
 
         old->next->prev = NULL;
         *l = old->next;
+        
         return old;
     }
 
@@ -87,8 +87,10 @@ struct dlist *dlist_delete_at(struct dlist **l, size_t index)
         old = tmp->next;
         tmp->prev = old->prev;
         tmp->next = old->next;
+        
         return old;
     }
+
     return NULL;
 }