implement working tree
This commit is contained in:
Joel Beckmeyer
parent
0b266e11ba
commit
474b0a6033
@ -1,9 +1,13 @@
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package termproject;
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import java.util.LinkedList;
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import java.util.Queue;
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import java.util.Random;
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/**
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* Title: Term Project 2-4 Trees
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* Description: An abstract data type for a 2-4 tree
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* Copyright: Copyright (c) 2001
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* Copyright: Copyright (c) 2017
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* @author Joel Beckmeyer & Daniel Parker
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* @version 1.0
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*/
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@ -28,7 +32,14 @@ public class TwoFourTree
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treeRoot = root;
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}
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private TFNode search(Object key) {
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/**
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* Searches the tree for a node containing the given key.
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*
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* @param key Object to search for
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* @return node which contains key, or insertion point for this key
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* @throws TwoFourTreeException if root is null
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*/
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private TFNode search(Object key) throws TwoFourTreeException {
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TFNode current = treeRoot;
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TFNode parent = null;
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if(treeRoot == null) {
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@ -39,9 +50,13 @@ public class TwoFourTree
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// we find the key
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while(current != null) {
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int index = FFGTE(current, key);
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// ensure that the index given is not out of bounds
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if(index != current.getNumItems()) {
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if(treeComp.isEqual(current.getItem(index).key(), key)) {
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break;
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}
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}
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parent = current;
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current = current.getChild(index);
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@ -56,9 +71,19 @@ public class TwoFourTree
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}
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}
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/**
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* Finds the index of the first item that is greater than or equal to the
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* given key.
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*
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* @param node TFnode to be searched
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* @param key key to find
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* @return index of first item greater than or equal to given key
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*/
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private int FFGTE(TFNode node, Object key) {
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int i;
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for(i = 0; i < node.getNumItems(); ++i) {
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// loop through item array, comparing each item until we find first item
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// greater than or equal to key
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for(i = 0; i < node.getNumItems(); i++) {
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if(treeComp.isGreaterThanOrEqualTo(node.getItem(i).key(), key)) {
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break;
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}
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@ -66,9 +91,16 @@ public class TwoFourTree
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return i;
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}
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/**
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* Finds the index of the given node in its parent.
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*
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* @param node the node to be found in the parent
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* @return index of node in its parent
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*/
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private int WCIT(TFNode node) {
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TFNode parent = node.getParent();
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int i;
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// loop through child array until we find the given node
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for(i = 0; i < parent.getNumItems() + 1; ++i) {
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if(parent.getChild(i) == node) {
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break;
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@ -77,27 +109,37 @@ public class TwoFourTree
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return i;
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}
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private TFNode getInOrderSuccessor(TFNode current, Object key) {
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if(current == null) {
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return null;
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/**
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* Finds the in-order successor of the given node-key combination.
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*
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* @param node the node to start at
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* @param key the key to follow
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* @return the in-order successor node
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*/
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private TFNode getInOrderSuccessor(TFNode node, int index) {
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TFNode parent = null;
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// go down the right child of our key
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TFNode current = node.getChild(index + 1);
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// go left until we hit a leaf
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while(current != null) {
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parent = current;
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current = current.getChild(0);
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}
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int index = FFGTE(current, key);
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TFNode next = getInOrderSuccessor(current.getChild(index), key);
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if(next == null) {
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return current;
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}else {
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return next;
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}
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return parent;
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}
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/**
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* Checks for and fixes node overflow.
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*
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* @param node the node to check for overflow
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*/
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private void fixOverflow(TFNode node) {
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if(node.getNumItems() <= MAX_ITEMS) {
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return;
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}
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TFNode left = node.getChild(3);
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TFNode right = node.getChild(4);
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TFNode parent = node.getParent();
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// special case when root overflows (we must increase height of tree)
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@ -110,15 +152,19 @@ public class TwoFourTree
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// removes offending data from current node
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int index = WCIT(node);
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// preserves data that we want to move around
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TFNode left = node.getChild(3);
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node.setChild(3, null);
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TFNode right = node.getChild(4);
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node.setChild(4, null);
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Item toSibling = node.deleteItem(3);
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Item toParent = node.deleteItem(2);
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node.setChild(3, null);
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node.setChild(4, null);
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// creates and populates new sibling node
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// creates and hooks up new sibling
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TFNode sibling = new TFNode();
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sibling.addItem(0, toSibling);
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sibling.setParent(parent);
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sibling.addItem(0, toSibling);
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sibling.setChild(0, left);
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sibling.setChild(1, right);
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if(left != null) {
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@ -126,14 +172,216 @@ public class TwoFourTree
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right.setParent(sibling);
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}
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// inserts data into parent node and hooks up sibling
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// connects children to parents
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parent.insertItem(index, toParent);
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parent.setChild(index, node);
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parent.setChild(index + 1, sibling);
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//}
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// recursively call on parent
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fixOverflow(parent);
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}
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/**
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* Checks for and fixes node underflow.
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*
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* @param node the node to check for underflow
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*/
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private void fixUnderflow(TFNode node) {
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// checks for underflow
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if(node.getNumItems() < 1) {
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// special case where root is underflowed
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if(node == treeRoot) {
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treeRoot = node.getChild(0);
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node.setParent(null);
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}
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// different cases to check and run
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else if(isPossibleLTrans(node)) {
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leftTransfer(node);
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}
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else if(isPossibleRTrans(node)) {
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rightTransfer(node);
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}
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else if(isPossibleLFusion(node)) {
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leftFusion(node);
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}
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else {
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rightFusion(node);
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}
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}
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}
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/**
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* Checks if left transfer is possible.
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*
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* @param node node to check for possible transfer
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* @return true if possible
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*/
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private boolean isPossibleLTrans(TFNode node) {
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// checks if the given node has a left sibling
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int index = WCIT(node);
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TFNode parent = node.getParent();
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if(index > 0) {
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TFNode sibling = parent.getChild(index - 1);
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// checks if existing left sibling has 2+ items
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return sibling.getNumItems() >= 2;
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}else {
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return false;
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}
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}
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/**
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* Checks if right transfer is possible.
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*
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* @param node node to check for possible transfer
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* @return true if possible
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*/
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private boolean isPossibleRTrans(TFNode node) {
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// checks if the given node has a right sibling
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int index = WCIT(node);
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TFNode parent = node.getParent();
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if(index < parent.getNumItems()) {
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TFNode sibling = parent.getChild(index + 1);
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// checks if existing right sibling has 2+ items
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return sibling.getNumItems() >= 2;
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}else {
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return false;
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}
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}
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/**
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* Performs a left transfer operation.
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*
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* @param node underflowed node to perform on
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*/
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private void leftTransfer(TFNode node) {
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int index = WCIT(node);
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TFNode parent = node.getParent();
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TFNode sibling = parent.getChild(index - 1);
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// preserving data that would otherwise be lost
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TFNode lastChild = sibling.getChild(sibling.getNumItems());
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sibling.setChild(sibling.getNumItems(), null);
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Item lastItem = sibling.deleteItem(sibling.getNumItems() - 1);
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// swap old sibling item with parent and add parent item to underflowed
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// node
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Item parentItem = parent.replaceItem(index - 1, lastItem);
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node.addItem(0, parentItem);
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// move old child 0 to child position 1, then add child from sibling as
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// child 0
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TFNode oldChild = node.getChild(0);
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node.setChild(1, oldChild);
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node.setChild(0, lastChild);
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if(lastChild != null) {
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lastChild.setParent(node);
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}
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}
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/**
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* Performs a right transfer operation.
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*
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* @param node underflowed node to perform on
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*/
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private void rightTransfer(TFNode node) {
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int index = WCIT(node);
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TFNode parent = node.getParent();
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TFNode sibling = parent.getChild(index + 1);
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// preserving data that would otherwise be lost
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TFNode firstChild = sibling.getChild(0);
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Item firstItem = sibling.removeItem(0);
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// swap old sibling item with parent and add parent item to underflowed
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// node
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Item parentItem = parent.replaceItem(index, firstItem);
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node.addItem(0, parentItem);
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// insert child from sibling as 2nd(index 1) child
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node.setChild(1, firstChild);
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if(firstChild != null) {
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firstChild.setParent(node);
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}
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}
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/**
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* Checks if left fusion operation is possible
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*
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* @param node node to check for possible fusion
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* @return true if possible
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*/
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private boolean isPossibleLFusion(TFNode node) {
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// checks if a left sibling exists
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return WCIT(node) > 0;
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}
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/**
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* Performs a left fusion operation
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*
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* @param node underflowed node to perform fusion on
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*/
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private void leftFusion(TFNode node) {
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int index = WCIT(node);
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TFNode parent = node.getParent();
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// delete underflowed node
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parent.setChild(index, null);
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// preserving data
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TFNode sibling = parent.getChild(index - 1);
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Item parentItem = parent.removeItem(index - 1);
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TFNode child = node.getChild(0);
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// insert data in sibling
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sibling.insertItem(sibling.getNumItems(), parentItem);
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sibling.setChild(sibling.getNumItems(), child);
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if(child != null) {
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child.setParent(sibling);
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}
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// fix parent pointer
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parent.setChild(index - 1, sibling);
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if(node == null) {
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System.out.println("node was null: ");
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}
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// recursively check underflow on parent
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fixUnderflow(parent);
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}
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/**
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* Performs a right fusion operation
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*
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* @param node underflowed node to perform fusion on
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*/
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private void rightFusion(TFNode node) {
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int index = WCIT(node);
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TFNode parent = node.getParent();
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// preserving data
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Item parentItem = parent.removeItem(index);
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TFNode child = node.getChild(0);
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TFNode sibling = parent.getChild(index);
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// insert data in sibling
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sibling.insertItem(0, parentItem);
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sibling.setChild(0, child);
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if(child != null) {
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child.setParent(sibling);
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}
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// recursively check underflow on parent
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fixUnderflow(parent);
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}
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public int size() {
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return size;
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}
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@ -172,12 +420,24 @@ public class TwoFourTree
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treeRoot = new TFNode();
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}
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TFNode node = getInOrderSuccessor(treeRoot, key);
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Item data = new Item(key, element);
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TFNode node = search(key);
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int index = FFGTE(node, key);
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node.insertItem(index, new Item(key, element));
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if(node.getNumItems() > MAX_ITEMS) {
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fixOverflow(node);
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if(index != node.getNumItems()) {
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// external node that contains a duplicate
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if(node.getChild(0) == null) {
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node.insertItem(index, data);
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// internal node that contains a duplicate
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}else {
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node = getInOrderSuccessor(node, index);
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node.insertItem(0, data);
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}
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// if we are at last index
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}else {
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node.insertItem(index, data);
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}
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fixOverflow(node);
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}
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/**
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@ -191,10 +451,27 @@ public class TwoFourTree
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TFNode node = search(key);
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int index = FFGTE(node, key);
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if(node.getItem(index).key() != key) {
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throw new ElementNotFoundException("element is not in tree");
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// if we are at an external node and we got the last index of node,
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// we know that the key was not in tree
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if(index == node.getNumItems() && node.getChild(0) == null) {
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this.printAllElements();
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throw new ElementNotFoundException("key is not in tree: " + key);
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}
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Object returnData;
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// if we are at an external node, simply remove data from node
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if(node.getChild(0) == null) {
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returnData = node.removeItem(index).element();
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// else, we are at an internal node, we must replace data with in-order
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// successor
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}else {
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TFNode successor = getInOrderSuccessor(node, index);
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returnData = node.replaceItem(index, successor.removeItem(0)).element();
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node = successor;
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}
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fixUnderflow(node);
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return returnData;
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}
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public static void main(String[] args) {
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@ -202,85 +479,120 @@ public class TwoFourTree
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TwoFourTree myTree = new TwoFourTree(myComp);
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myTree.insertElement(47, 47);
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myTree.printAllElements();
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myTree.insertElement(83, 83);
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myTree.printAllElements();
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myTree.insertElement(22, 22);
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myTree.printAllElements();
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myTree.insertElement(16, 16);
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myTree.printAllElements();
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myTree.insertElement(49, 49);
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myTree.printAllElements();
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myTree.insertElement(100, 100);
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myTree.printAllElements();
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myTree.insertElement(38, 38);
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myTree.printAllElements();
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myTree.insertElement(3, 3);
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myTree.printAllElements();
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myTree.insertElement(53, 53);
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myTree.printAllElements();
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myTree.insertElement(66, 66);
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myTree.printAllElements();
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myTree.insertElement(19, 19);
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myTree.printAllElements();
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myTree.insertElement(23, 23);
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myTree.printAllElements();
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myTree.insertElement(24, 24);
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myTree.printAllElements();
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myTree.insertElement(88, 88);
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myTree.printAllElements();
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myTree.insertElement(1, 1);
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myTree.printAllElements();
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myTree.insertElement(97, 97);
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myTree.printAllElements();
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myTree.insertElement(94, 94);
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myTree.printAllElements();
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myTree.insertElement(35, 35);
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myTree.printAllElements();
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myTree.insertElement(51, 51);
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myTree.printAllElements();
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System.out.println("done");
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//myTree.printAllElements();
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//System.out.println("removing\n");
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/*myTree = new TwoFourTree(myComp);
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final int TEST_SIZE = 10000;
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myTree.removeElement(19);
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myTree.removeElement(66);
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myTree.removeElement(100);
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myTree.removeElement(83);
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myTree.removeElement(51);
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myTree.removeElement(94);
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myTree.removeElement(49);
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myTree.removeElement(88);
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//myTree.printAllElements();
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System.out.println("test 1: simple test done");
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for (int i = 0; i < TEST_SIZE; i++) {
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myTree.insertElement(new Integer(i), new Integer(i));
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myTree.printAllElements();
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myTree.checkTree();
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System.out.println();
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myTree = new TwoFourTree(myComp);
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int testSize = 10000;
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Random rng = new Random();
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Queue<Integer> nums = new LinkedList<Integer>();
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for (int i = 0; i < testSize; i++) {
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int j = rng.nextInt(testSize / 10);
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nums.add(j);
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myTree.insertElement(j, j);
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// if(i > testSize - 30) {
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// System.out.println("inserting " + j);
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// myTree.printAllElements();
|
||||
// myTree.checkTree();
|
||||
// }
|
||||
}
|
||||
System.out.println("removing");
|
||||
for (int i = 0; i < TEST_SIZE; i++) {
|
||||
int out = (Integer) myTree.removeElement(new Integer(i));
|
||||
if (out != i) {
|
||||
throw new TwoFourTreeException("main: wrong element removed");
|
||||
for (int i = testSize - 1; i >= 0; i--) {
|
||||
int j = nums.remove();
|
||||
if (i < 30){
|
||||
System.out.println("removing "+j);
|
||||
}
|
||||
if (i > TEST_SIZE - 15) {
|
||||
//myTree.printAllElements();
|
||||
int out = (int)myTree.removeElement(j);
|
||||
if (out != j) {
|
||||
throw new TwoFourTreeException("main: wrong element removed: " + out +" ; " + j);
|
||||
}
|
||||
if (i < 30){
|
||||
myTree.printAllElements();
|
||||
}
|
||||
|
||||
}
|
||||
*/
|
||||
System.out.println("done");
|
||||
System.out.println("test 2: random done");
|
||||
myTree.printAllElements();
|
||||
|
||||
System.out.println();
|
||||
myTree = new TwoFourTree(myComp);
|
||||
testSize = 1000;
|
||||
for (int i = 0; i < testSize; i++) {
|
||||
myTree.insertElement(0, 0);
|
||||
}
|
||||
System.out.println("removing");
|
||||
int out;
|
||||
for (int i = testSize - 1; i >= 0; i--) {
|
||||
out = (int)myTree.removeElement(0);
|
||||
if (out != 0) {
|
||||
throw new TwoFourTreeException("main: wrong element removed: " + out);
|
||||
}
|
||||
}
|
||||
System.out.println("test 3: extreme duplicate test done");
|
||||
myTree.printAllElements();
|
||||
|
||||
System.out.println();
|
||||
for (int i = 0; i < testSize; i++) {
|
||||
myTree.insertElement(i, i);
|
||||
}
|
||||
System.out.println("removing");
|
||||
for (int i = testSize - 1; i >= 0; i--) {
|
||||
out = (int)myTree.removeElement(i);
|
||||
if (out != i) {
|
||||
throw new TwoFourTreeException("main: wrong element removed: " + out +" ; " + i);
|
||||
}
|
||||
}
|
||||
System.out.println("test 4: reverse sorted order remove done");
|
||||
myTree.printAllElements();
|
||||
|
||||
System.out.println();
|
||||
for (int i = 0; i < testSize; i++) {
|
||||
myTree.insertElement(i, i);
|
||||
}
|
||||
System.out.println("removing");
|
||||
for (int i = 0; i < testSize; i++) {
|
||||
out = (int)myTree.removeElement(i);
|
||||
if (out != i) {
|
||||
throw new TwoFourTreeException("main: wrong element removed: " + out +" ; " + i);
|
||||
}
|
||||
}
|
||||
System.out.println("test 5: sorted order remove done");
|
||||
myTree.printAllElements();
|
||||
|
||||
}
|
||||
|
||||
public void printAllElements() {
|
||||
|
||||
Loading…
Reference in New Issue
Block a user