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import edu.princeton.cs.algs4.Queue;
/**
* 二叉查找树的实现
*
* @author elong
* @version V1.0
* @date 2018/1/23
*/
public class BST<Key extends Comparable<Key>, Value> {
private Node root;
private class Node {
private final Key key;
private Value value;
private Node left, right;
private int count;
public Node(Key key, Value value) {
this.key = key;
this.value = value;
this.count = 1;
}
@Override
public String toString() {
return key + " : " + value;
}
}
public void put(Key key, Value value) {
root = put(root, key, value);
}
private Node put(Node x, Key key, Value value) {
if (x == null) {
return new Node(key, value);
}
int cmp = key.compareTo(x.key);
if (cmp < 0) {
x.left = put(x.left, key, value);
}
if (cmp > 0) {
x.right = put(x.right, key, value);
}
if (cmp == 0) {
x.value = value;
}
x.count = 1 + size(x.left) + size(x.right);
return x;
}
public Value get(Key key) {
Node x = root;
while (x != null) {
int cmp = key.compareTo(x.key);
if (cmp < 0) {
x = x.left;
} else if (cmp > 0) {
x = x.right;
} else {
return x.value;
}
}
return null;
}
public int size() {
return size(root);
}
private int size(Node node) {
if (node == null) {
return 0;
}
return node.count;
}
public Key minKey() {
Node node = minKey(root);
if (node == null) return null;
return node.key;
}
private Node minKey(Node node) {
if (node.left == null) {
return node;
}
return minKey(node.left);
}
public Key maxKey() {
Node node = maxKey(root);
if (node == null) return null;
return node.key;
}
private Node maxKey(Node node) {
if (node.right == null) {
return node;
}
return maxKey(node.right);
}
/**
* 小于等于给定Key的最大值
*/
public Key floor(Key key) {
Node node = floor(root, key);
if (node == null) return null;
return node.key;
}
private Node floor(Node node, Key key) {
if (node == null) return null;
int cmp = key.compareTo(node.key);
if (cmp == 0) {
return node;
}
if (cmp < 0) {
return floor(node.left, key);
}
Node x = floor(node.right, key);
if (x != null) {
return x;
}
return node;
}
/**
* 大于等于给定Key的最小值
*/
public Key ceiling(Key key) {
Node node = ceiling(root, key);
if (node == null) {
return null;
}
return node.key;
}
private Node ceiling(Node node, Key key) {
if (node == null) return null;
int cmp = key.compareTo(node.key);
if (cmp == 0) {
return node;
}
if (cmp > 0) {
return ceiling(node.right, key);
}
Node x = ceiling(node.left, key);
if (x != null) {
return x;
}
return node;
}
/**
* 小于Key的Node的数量
*/
public int rank(Key key) {
return rank(root, key);
}
private int rank(Node node, Key key) {
if (node == null) {
return 0;
}
int cmp = key.compareTo(node.key);
if (cmp == 0) {
return size(node.left);
}
if (cmp > 0) {
return 1 + size(node.left) + rank(node.right, key);
}
return rank(node.left, key);
}
public Iterable<Key> keys() {
Queue<Key> q = new Queue<>();
inorder(root, q);
return q;
}
private void inorder(Node node, Queue<Key> q) {
if (node == null) {
return;
}
inorder(node.left, q);
q.enqueue(node.key);
inorder(node.right, q);
}
public void delete(Key key) {
delete(root, key);
}
private Node delete(Node node, Key key) {
if (node == null) {
return null;
}
int cmp = key.compareTo(node.key);
if (cmp < 0) {
node.left = delete(node.left, key);
} else if (cmp > 0) {
node.right = delete(node.right, key);
} else {
if (node.right == null) return node.left;
if (node.left == null) return node.right;
Node t = node;
node = minKey(t.right);
node.right = delMin(t.right);
node.left = t.left;
}
node.count = 1 + size(node.left) + size(node.right);
return node;
}
public void delMin() {
delMin(root);
}
private Node delMin(Node node) {
if (node.left == null) {
return node.right;
}
node.left = delMin(node.left);
node.count = 1 + size(node.left) + size(node.right);
return node;
}
public static void main(String[] args) {
BST<String, String> bst = new BST<>();
bst.put("b", "b");
bst.put("c", "c");
bst.put("d", "d");
bst.put("e", "e");
bst.put("u", "r");
bst.put("f", "r");
bst.put("y", "r");
bst.put("v", "r");
bst.put("v", "r");
bst.put("v", "r");
bst.put("a", "r");
System.out.println(bst.ceiling("a"));
System.out.println(bst.maxKey());
System.out.println(bst.size());
System.out.println(bst.rank("z"));
bst.delMin();
for (String s : bst.keys()) {
System.out.println(s);
}
}
}
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