2-3 Deletion (Case #2)

How do we delete an element present at an internal node? It will be explained in this lesson with the help of an example.

We'll cover the following

Case 2: Element at Internal Node:

Deletion is always performed at the leaf. So whenever we need to delete a key at the internal node, we swap it with any of its in-order successors and somehow make it shift to any leaf node as deletion is always performed at the leaf. Shift the element at the leaf node and then delete it. The element to be deleted can be swapped by:

  • an element with the largest key on the left
  • an element with the smallest key on the right

This is applicable when the child node has more than one key stored at the node. If there is only one value at the child node, then you are bound to swap the parent with whatever value the child node has.

Example

See the following illustration which covers the two scenarios that we discussed above:

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