Added nodeID counter for easier reference in rotation. (4734045c) · Commits · EC504 / HW3 / hw3p1

src/edu/bu/ec504/hw2/BST.java

+14 −7

Original line number	Diff line number	Diff line
		package edu.bu.ec504.hw2;

		import java.util.ArrayList;
		import java.util.Iterator;

		/**
		* Implements a simple (not necessarily balanced) Binary Search Tree.
		@@ -18,6 +19,7 @@ public class BST<keyType extends Comparable<keyType> > {
		key = null;
		left = null;
		right = null;
		nodeId=nodeIdCounter++;
		}

		/**
		@@ -46,16 +48,20 @@ public class BST<keyType extends Comparable<keyType> > {

		// METHODS

		// ... getters
		final Integer getNodeId() { return nodeId; }
		final keyType getKey() { return key; }

		/**
		* Compute how to transform this BST into the BST <code>otherTree</code> using rotations.
		* Compute how to transform this BST into the BST {@code otherTree} using rotations.
		*
		* @param otherTree The into which we seek to transform the current tree.
		* @expects The keys of this object are {@link #equals(Object)}} to the keys of <code>otherTree</code>
		* @expects The keys of this object are {@link #equals(Object)}} to the keys of {@code otherTree}
		* in a one-to-one correspondence.
		* @return An ArrayList of rotations indicating which rotations around which nodes
		* must be performed to transform <first> into <second.
		* must be performed to transform this object into {@code otherTree}
		*/
		public ArrayList<BstRotation<keyType> > transformTo(BST<keyType> otherTree) {
		public ArrayList<BstRotation> transformTo(BST<keyType> otherTree) {
		throw new UnsupportedOperationException("This method should be properly implemented in a subclass.");
		}

		@@ -98,7 +104,7 @@ public class BST<keyType extends Comparable<keyType> > {

		/**
		* Return the BST rooted at this node as a human-readable string,
		* indented by <code>depth</code> characters
		* indented by {@code depth} characters
		*
		* @param prefix The current prefix for the subtree being printed
		*/
		@@ -106,7 +112,7 @@ public class BST<keyType extends Comparable<keyType> > {
		String result = "";

		// output the key
		result += key + "\n";
		result += key + "(ID "+nodeId+")\n";

		// recurse
		result += prefix + "->" + (left == null ? "\n" : left.toString(prefix.concat(" \|")));
		@@ -119,5 +125,6 @@ public class BST<keyType extends Comparable<keyType> > {
		protected keyType key; // the key stored by this node
		protected BST<keyType> left; // the left child of this node
		protected BST<keyType> right; // the right child of this node

		private Integer nodeId; // the current node ID
		private static Integer nodeIdCounter=0; // a counter for node IDs
		}

src/edu/bu/ec504/hw2/BstRotation.java

+9 −11

Original line number	Diff line number	Diff line
		package edu.bu.ec504.hw2;

		import java.util.Iterator;

		/**
		* Represents one rotation (ZIG or ZAG) around one key in a Binary Search Tree
		*/
		public class BstRotation<keyType> {
		public class BstRotation {
		public enum RotationType {ZIG, ZAG}

		public BstRotation(Iterator<keyType> rootOfRot, RotationType rotType) {
		RotRoot = rootOfRot;
		myRotType = rotType;
		public BstRotation(Integer myRotRootID, RotationType myRotType) {
		rotRootID = myRotRootID;
		rotType = myRotType;
		}

		/**
		* @return A human-readable description of the rotation
		*/
		public String print() {
		public String toString() {
		String result = "";
		switch (myRotType) {
		switch (rotType) {
		case ZIG:
		result = "ZIG";
		break;
		@@ -26,10 +24,10 @@ import java.util.Iterator;
		result = "ZAG";
		break;
		}
		result += " on " + RotRoot;
		result += " on node ID "+ rotRootID;
		return result;
		}

		private final Iterator<keyType> RotRoot; // the root of the rotation being performed
		private final RotationType myRotType; // the type of rotation being performed
		private final Integer rotRootID; // the ID of the root of the rotation being performed
		private final RotationType rotType; // the type of rotation being performed
		}

src/edu/bu/ec504/hw2/Main.java

+2 −0

Original line number	Diff line number	Diff line
		@@ -13,5 +13,7 @@ class Main {

		System.out.println("Your int BST is:\n"+intTest);
		System.out.println("Your string BST is:\n"+strTest);
		System.out.println("One rotation: "+new BstRotation(3, BstRotation.RotationType.ZAG));

		}
		}