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c#linked-list

Remove node from single linked list


as far as I can see, you can do:

  1. Find the node to remove.
  2. node.previous.next = node.next
  3. node.next.previous = node.previous
  4. node.previous = null
  5. node.next = null
  6. Dispose of node if you're in a non-GC environment

If your list is a double linked.

But how do you do it with a single linked list? I have tried a lot of things, with no avail :( I simply get it to remove a specific index instead or it does nothing at all


Solution

  • Start at the beginning of the list. Maintain a reference to the current item (currentItem) and the previous item (previousItem). Linearly search for the item that you want to remove always walking with previousItem = currentItem, currentItem = currentItem.Next. If the item that you want to remove is the head of the list, reassign the head of the list to currentItem.Next. Otherwise, set previousItem.Next = currentItem.Next. If necessary (as you say, in a non-GC environment) dispose of currentItem.

    Basically you are using previousItem to mimic the behavior of a currentItem.Previous in the case of a doubly-linked list.

    Edit: This is a correct implementation of Delete:

    public void Delete(int rangeStart, int rangeEnd) {
        Node previousNode = null, currentNode = Head;
        while (currentNode != null) {
            if (currentNode.Data >= rangeStart && currentNode.Data <= rangeEnd) {
                if (previousNode == null) {
                    Initial = currentNode.Next;
                }
                else {
                    previousNode.Next = currentNode.Next;
                }
            }
            else {
                previousNode = currentNode;
            }
            currentNode = currentNode.Next;
        }
    }