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BST.java
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313 lines (244 loc) · 8.03 KB
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import java.util.StringTokenizer;
/**
* Created by Phil on 8/7/2015.
*/
public class BST<Key extends Comparable<Key>, Value> {
private class Tree {
Key key;
Value value;
Tree left;
Tree right;
private Tree(Key key, Value value) {
this.key = key;
this.value = value;
left = null;
right = null;
}
}
Tree root;
public BST() {
root = null;
}
public Value get(Key thing) {
Tree current = root;
while(current != null) {
int compare = thing.compareTo(current.key);
if(compare < 0) current = current.left;
else if(compare > 0) current = current.right;
else return current.value;
}
return null;
}
public void put(Key key, Value value) {
root = put(key, value, root);
}
private Tree put(Key key, Value value, Tree node) {
if(node == null) {
return new Tree(key, value);
}
int compare = key.compareTo(node.key);
if(compare < 0) node.left = put(key, value, node.left);
else if(compare > 0) node.right = put(key, value, node.right);
else node.value = value;
return node;
}
public void delete(Key key) {
root = delete(key, root);
}
private Tree delete(Key key, Tree node) {
if(node == null)
return null;
int compare = key.compareTo(node.key);
if(compare < 0) node.left = delete(key, node.left);
else if(compare > 0) node.right = delete(key, node.right);
else {
Tree tempNode = node;
node = getMin(tempNode.right);
node.right = deleteMin(tempNode.right);
node.left = tempNode.left;
}
return node;
}
private Tree getMin(Tree node) {
if(node == null) {
System.out.println("Error! Trying to get min of null tree!");
return null;
}
while(node.left != null)
node = node.left;
return node;
}
private Tree deleteMin(Tree node) {
if(node.left == null)
return node.right;
node.left = deleteMin(node.left);
return node;
}
public Tree floor(Key key) {
return floor(key, root);
}
private Tree floor(Key key, Tree node) {
if(node == null) return null;
int compare = key.compareTo(node.key);
if(compare == 0) return node;
else if(compare < 0) return floor(key, node.left);
else {
Tree possibleFloor = floor(key, node.right);
if(possibleFloor == null)
return node;
else
return possibleFloor;
}
}
public Tree ceiling(Key key) {
return ceiling(key, root);
}
private Tree ceiling(Key key, Tree node) {
if(node == null) return null;
int compare = key.compareTo(node.key);
if(compare == 0) return node;
else if(compare > 0) return ceiling(key, node.right);
else {
Tree possibleCeiling = ceiling(key, node.left);
if(possibleCeiling == null)
return node;
else
return possibleCeiling;
}
}
public boolean isEmpty() {
return root == null;
}
public Iterable<Key> keys() {
ArrayQueue<Key> queue = new ArrayQueue();
inOrder(root, queue);
return queue;
}
public String serialize() {
StringBuilder builder = new StringBuilder();
serialize(root, builder);
return builder.toString();
}
private void serialize(Tree node, StringBuilder builder) {
if(node == null) {
builder.append("# ");
return;
}
builder.append(node.key + ":" + node.value + " ");
serialize(node.left, builder);
serialize(node.right, builder);
}
public void deserialize(String serializedTree) {
StringTokenizer tokenizer = new StringTokenizer(serializedTree);
root = null;
if(tokenizer.hasMoreTokens()) {
root = deserialize(root, tokenizer);
}
}
private Tree deserialize(Tree node, StringTokenizer tokenizer) {
if(!tokenizer.hasMoreTokens())
return null;
String token = tokenizer.nextToken();
if(token.equals("#")) {
return null;
}
String[] parts = token.split(":");
Key key = (Key)(Object) Integer.parseInt(parts[0]);
Value value = (Value)(Object) parts[1];
Tree newNode = new Tree(key, value);
newNode.left = deserialize(newNode.left, tokenizer);
newNode.right = deserialize(newNode.right, tokenizer);
return newNode;
}
public void preOrder(Tree node, ArrayQueue queue) {
if(node == null)
return;
queue.enqueue(node);
preOrder(node.left, queue);
preOrder(node.right, queue);
}
public void inOrder(Tree node, ArrayQueue queue) {
if(node == null)
return;
inOrder(node.left, queue);
queue.enqueue(node.key);
inOrder(node.right, queue);
}
public void postOrder(Tree node, ArrayQueue queue) {
if(node == null)
return;
postOrder(node.left, queue);
postOrder(node.right, queue);
queue.enqueue(node.key);
}
public void levelOrderTraversal() {
Tree current = root;
LinkedListQueue<Tree> queue = new LinkedListQueue<Tree>();
queue.enqueue(current);
while (!queue.isEmpty()) {
current = queue.dequeue();
System.out.println(current.value);
if(current.left != null)
queue.enqueue(current.left);
if(current.right != null)
queue.enqueue(current.right);
}
}
public static void main(String[] args) {
BST<Integer, String> tree = new BST();
tree.put(10, "ten");
tree.put(14, "fourteen");
tree.put(4, "four");
tree.put(3, "three");
tree.put(7, "seven");
tree.put(11, "eleven");
tree.put(6, "six");
tree.put(13, "thirteen");
tree.put(20, "twenty");
tree.put(1, "one");
tree.put(8, "eight");
tree.put(15, "fifteen");
tree.put(5, "five");
tree.put(9, "nine");
tree.put(12, "twelve");
System.out.println("Keys:");
for(Integer k : tree.keys()) {
System.out.println(k + ": " + tree.get(k));
}
System.out.println("Level order traversal:");
tree.levelOrderTraversal();
System.out.println("Get: 2, 6, 4, 20: ");
System.out.println(tree.get(2));
System.out.println(tree.get(6));
System.out.println(tree.get(4));
System.out.println(tree.get(20));
System.out.println("floor 4:");
System.out.println(tree.floor(4).value);
System.out.println("ceiling 4:");
System.out.println(tree.ceiling(4).value);
System.out.println("deleting 4...");
tree.delete(4);
System.out.println("get 4:");
System.out.println(tree.get(4));
System.out.println("floor 4:");
System.out.println(tree.floor(4).value);
System.out.println("ceiling 4:");
System.out.println(tree.ceiling(4).value);
String serialized = tree.serialize();
System.out.println("Serialized: ");
System.out.println(serialized);
BST<Integer, String> tree2 = new BST();
tree2.deserialize(serialized);
System.out.println("Level order traversal...");
tree2.levelOrderTraversal();
System.out.println("floor 4:");
System.out.println(tree2.floor(4).value);
System.out.println("ceiling 4:");
System.out.println(tree2.ceiling(4).value);
System.out.println("Get: 2, 6, 4, 20: ");
System.out.println(tree2.get(2));
System.out.println(tree2.get(6));
System.out.println(tree2.get(4));
System.out.println(tree2.get(20));
}
}