2-3-4 树 Java数据结构与算法

2-3-4 树 Java数据结构与算法

 

源代码：

 

/** * * @author sunnyykn */import java.io.*;class DataItem{ public long dData; //one data item public DataItem(long dd) { dData = dd; } public void displayItem() { System.out.print("/" + dData); }}class Node{ private static final int ORDER = 4; private int numItems; private Node parent; private Node childArray[] = new Node[ORDER]; private DataItem itemArray[] = new DataItem[ORDER - 1]; public void connectChild(int childNum,Node child) { childArray[childNum] = child; if(child != null) { child.parent = this; } } public Node disconnectChild(int childNum) { Node tempNode = childArray[childNum]; childArray[childNum] = null; return tempNode; } public Node getChild(int childNum) { return childArray[childNum]; } public Node getParent() { return parent; } public boolean isLeaf() { return (childArray[0] == null) ? true : false ; } public int getNumItems() { return numItems; } public DataItem getItem(int index) { return itemArray[index]; } public boolean isFull() { return (numItems == ORDER - 1) ? true : false ; } public int findItem(long key) { for(int j = 0; j < ORDER - 1;j ++) { if(itemArray[j] == null) break; else if(itemArray[j].dData == key) return j; } return -1; } public int insertItem(DataItem newItem) { numItems ++; long newKey = newItem.dData; for(int j = ORDER - 2;j >= 0;j --) { if(itemArray[j] == null) continue; else { long itsKey = itemArray[j].dData; if(newKey < itsKey) itemArray[j + 1] = itemArray[j]; else { itemArray[j + 1] = newItem; return j + 1; } } } itemArray[0] = newItem; return 0; } public DataItem removeItem() { DataItem temp = itemArray[numItems - 1]; itemArray[numItems - 1] = null; numItems --; return temp; } public void displayNode() { for(int j = 0;j < numItems;j ++) itemArray[j].displayItem(); System.out.println("/"); }}//end class Nodeclass Tree234{ private Node root = new Node(); public int find(long key) { Node curNode = root; int childNumber; while(true) { if((childNumber = curNode.findItem(key)) != -1) return childNumber; else if( curNode.isLeaf() ) return -1; else curNode = getNextChild(curNode,key); } } public void insert(long dValue) { Node curNode = root; DataItem tempItem = new DataItem(dValue); while(true) { if(curNode.isFull()) { split(curNode); curNode = curNode.getParent(); curNode = getNextChild(curNode,dValue); } else if(curNode.isLeaf()) { break; } else curNode = getNextChild(curNode,dValue); } curNode.insertItem(tempItem); } public void split(Node thisNode) { //assumes node is full DataItem itemB,itemC; Node parent, child2, child3; int itemIndex; itemC = thisNode.removeItem(); itemB = thisNode.removeItem(); child2 = thisNode.disconnectChild(2); child3 = thisNode.disconnectChild(3); Node newRight = new Node(); if(thisNode == root) { root = new Node(); parent = root; root.connectChild(0, thisNode); } else parent = thisNode.getParent(); itemIndex = parent.insertItem(itemB); int n = parent.getNumItems(); for(int j = n - 1;j > itemIndex;j --) { Node temp = parent.disconnectChild(j); parent.connectChild(j + 1, temp); } parent.connectChild(itemIndex + 1, newRight); newRight.insertItem(itemC); newRight.connectChild(0, child2); newRight.connectChild(1, child3); } public Node getNextChild(Node theNode,long theValue) { int j; int numItems = theNode.getNumItems(); for(j = 0 ;j < numItems ; j ++) { if(theValue < theNode.getItem(j).dData) return theNode.getChild(j); } return theNode.getChild(j); } public void displayTree() { recDisplayTree(root,0,0); } private void recDisplayTree(Node thisNode,int level,int childNumber) { System.out.print("level = " + level + " child = " + childNumber + " "); thisNode.displayNode(); int numItems = thisNode.getNumItems(); for(int j = 0;j < numItems + 1;j ++) { Node nextNode = thisNode.getChild(j); if(nextNode != null) recDisplayTree(nextNode,level + 1,j); else return; } }}//end class Tree234class Tree234App{ public static void main(String[] args) throws IOException { long value; Tree234 theTree = new Tree234(); theTree.insert(50); theTree.insert(40); theTree.insert(60); theTree.insert(30); theTree.insert(70); while(true) { System.out.print("Enter first letter of show, insert, or find :"); char choice = getChar(); switch(choice) { case 's': theTree.displayTree(); break; case 'i': System.out.print("Enter value to insert:"); value = getInt(); theTree.insert(value); break; case 'f': System.out.print("Enter value to find:"); value = getInt(); int found = theTree.find(value); if(found != -1) System.out.println("Found " + value); else System.out.println("Could not find " + value); break; default: System.out.println("Invalid entry/n"); } } } public static String getString() throws IOException { InputStreamReader isr = new InputStreamReader(System.in); BufferedReader br = new BufferedReader(isr); String s = br.readLine(); return s; } public static char getChar() throws IOException { String s = getString(); return s.charAt(0); } public static int getInt() throws IOException { String s = getString(); return Integer.parseInt(s); }}