Core code for splitting 2-3-4 trees [JAVA Implementation]

2-3-4 Tree nodes are split into two types.

1: node split; 2: Root split.

Set the data items to be split to A, B, and C.

Node splitting

1. Create a New empty node. It is the brother of the node to be split, on the right of the node to be split.

2. data item C is transferred to the new node.

3. data item B is transferred to the parent node of the node to be split.

4. data item A is retained on the original node.

5. the rightmost two subnodes are disconnected from the node to be split and connected to the new node.

Root split

1. Create a new node as the root node. It is the parent node of the node to be split.

2. Create the second empty node. It is the brother of the node to be split, on the right of the node to be split.

3. data item C is transferred to the new node.

4. data item B is transferred to the parent node of the node to be split.

5. data item A is retained on the original node.

6. the rightmost two subnodes are disconnected from the split node and connected to the new node.

Code Public void split (node thisnode) // split the node <br/> {<br/> // assumes node is full <br/> dataitem itemb, itemc; // data item B, C <br/> node parent, child2, Child3; // The parent node of the thisnode, which contains 3rd and 4 subnodes <br/> int itemindex; </P> <p> itemc = thisnode. removeitem (); // data item C is removed from the thisnode <br/> itemb = thisnode. removeitem (); // data item B is removed from the thisnode </P> <p> child2 = thisnode. disconnectchild (2); // The 3rd sub-nodes of the node are disconnected from the node <br/> Child3 = Thisnode. disconnectchild (3); // 4th sub-nodes of a node are disconnected from the node </P> <p> node newright = new node (); // make new node </P> <p> If (thisnode = root) // create a new node as the root node. It is the parent node of the node to be split. <Br/> {<br/> root = new node (); // make new root <br/> parent = root; // root is our parent <br/> root. connectchild (0, thisnode); // connect to parent <br/>}< br/> else // This node not the root <br/> parent = thisnode. getparent (); // obtain the parent node of the node </P> <p> // deal with parent <br/> itemindex = parent. insertitem (itemb); // insert data item B to the parent node and return the inserted position. <br/> int n = parent. getnumitems (); // total data items of the parent node </P> <p>/* <br/> * move the child node of the parent node to the appropriate location <br/> */<br/> for (Int J = n-1; j> itemindex; j --) // move parent's <br/> {// connections <br/> node temp = parent. disconnectchild (j); // One Child <br/> parent. connectchild (J + 1, temp); // to the right <br/>}< br/> // connect newright to parent <br/> parent. connectchild (itemindex + 1, newright); // The new node is connected to the parent node </P> <p> // deal with newright <br/> newright. insertitem (itemc); // item C to newright <br/> newright. connectchild (0, child2); // connect to 0 and 1 <br/> newright. connectchild (1, Child3); // on newright <br/>}// end split () <br/>