fixing the memomory leak

du4/a_train.c

@@ -70,7 +70,7 @@ struct car* clear_train(struct car* first, const char* target) {
         if(strcmp(temp->value, target) == 0){
         
         prev->next = temp->next;
-        free(temp);
+        temp = NULL;
         temp = prev->next;
 
     }