public interface Map<K, V>
{
void add(K key, V value);
V remove(K key);
bool contains(K key);
V get(K key);
void set(K key, V value);
int getSize();
bool isEmpty();
}
public class BSTMap<K, V> : Map<K, V> where K : System.IComparable<K>
{
public class Node
{
public K key;
public V value;
public Node left, right;
public Node(K key, V value)
{
this.key = key;
this.value = value;
left = null;
right = null;
}
public override string ToString()
{
return key.ToString() + ":" + value.ToString();
}
}
private Node root;
private int size;
public BSTMap()
{
root = null;
size = 0;
}
/// <summary>
/// 向二分搜索树添加新的元素
/// </summary>
/// <param name="key"></param>
/// <param name="value"></param>
public void add(K key, V value)
{
root = add(root, key, value);
}
/// <summary>
/// 向以node为跟的二分搜搜树种插入 key value 的元素 递归算法 插入新的节点后为二分搜索树的跟
/// </summary>
/// <param name="node"></param>
/// <param name="key"></param>
/// <param name="value"></param>
/// <returns></returns>
private Node add(Node node, K key, V value)
{
if (node == null)
{
size++;
return new Node(key, value);
}
if (key.CompareTo(node.key) < 0)
node.left = add(node.left, key, value);
else if (key.CompareTo(node.key) > 0)
node.right = add(node.right, key, value);
else
node.value = value;
return node;
}
/// <summary>
/// 返回以node 为根节点的二分搜索树种
/// </summary>
/// <param name="node"></param>
/// <param name="key"></param>
/// <returns></returns>
private Node GetNode(Node node, K key)
{
if (node == null)
{
return null;
}
if (key.CompareTo(node.key) == 0)
{
return node;
}
else if (key.CompareTo(node.key) < 0)
{
return GetNode(node.left, key);
}
else // (key.CompareTo(node.key) < 0)
{
return GetNode(node.right, key);
}
}
public bool contains(K key)
{
Node node = GetNode(root, key);
return node != null;
}
public V get(K key)
{
Node node = GetNode(root, key);
return node == null ? default(V) : node.value;
}
public int getSize()
{
return size;
}
public bool isEmpty()
{
return size == 0;
}
public V remove(K key)
{
Node node = GetNode(root, key);
if (node != null)
{
root = remove(root, key);
return node.value;
}
return default(V);
}
private Node remove(Node node, K key)
{
if (node == null)
return null;
if (key.CompareTo(node.key) < 0)
{
node.left = remove(node.left, key);
return node;
}
else if (key.CompareTo(node.key) > 0)
{
node.right = remove(node.right, key);
return node;
}
else // key ==node.key
{
//待删除左子树为空的情况
if (node.left == null)
{
Node rightNode = node.right;
node.right = null;
size--;
return rightNode;
}
//待删除节点右子树为空的情况
if (node.right == null)
{
Node lefyNode = node.left;
node.left = null;
size--;
return lefyNode;
}
// 待删除节点左右孩子均不为空的情况
//找到比待删除节点大的最小值的节点， 即待删除节点右子树的最小节点
//用这个节点顶替待删除的节点位置
Node successor = minimum(node.right);
successor.right = removeMin(node.right);
successor.left = node.left;
node.left = node.right = null;
return successor;
}
}
/// <summary>
/// 返回以node为跟的二分搜索树的最小值所在的节点
/// </summary>
/// <param name="node"></param>
/// <returns></returns>
private Node minimum(Node node)
{
if (node.left == null)
return node;
return minimum(node.left);
}
/// <summary>
/// 删除掉以node为跟的二分搜索树种最小的节点
/// /// </summary>
/// <param name="node"></param>
/// <returns>返回删除节点后更新的二分搜索树的根</returns>
private Node removeMin(Node node)
{
if (node.left == null)
{
Node rightNode = node.right;
node.right = null;
size--;
return rightNode;
}
node.left = removeMin(node.left);
return node;
}
public void set(K key, V value)
{
Node node = GetNode(root, key);
if (node == null)
{
add(key, value);
}
else
{
node.value = value;
}
}
}
public class Trie
{
public class Node
{
/// <summary>
/// 单词结尾赋值 value
/// </summary>
public int value;
public BSTMap<char, Node> next;
public Node(int value = 0)
{
value = 0;
next = new BSTMap<char, Node>();
}
public Node() : this(0) { }
}
private Node root;
public Trie()
{
root = new Node();
}
public void add(string key, int value = 1)
{
Node cur = root;
for (var i = 0; i < key.Length; i++)
{
char c = key[i];
if (cur.next.get(c) == null)
{
cur.next.add(c, new Node());
}
cur = cur.next.get(c);
}
cur.value = value;
}
}
