add HashTable

Author: hackfengJam

HashTable/pride-and-prejudice.txt

@@ -0,0 +1,348 @@
+import java.util.ArrayList;
+
+public class AVLTree<K extends Comparable<K>, V> {
+
+    private class Node {
+        public K key;
+        public V value;
+        public Node left, right;
+        public int height;
+
+        public Node(K key, V value) {
+            this.key = key;
+            this.value = value;
+            left = null;
+            right = null;
+            height = 1;
+        }
+    }
+
+    private Node root;
+    private int size;
+
+    public AVLTree() {
+        root = null;
+        size = 0;
+    }
+
+    public int getSize() {
+        return size;
+    }
+
+    public boolean isEmpty() {
+        return size == 0;
+    }
+
+    // 判断该二叉树是否是一棵二分搜索树
+    public boolean isBST() {
+        ArrayList<K> keys = new ArrayList<>();
+        inOrder(root, keys);
+        for (int i = 1; i < keys.size(); i++) {
+            if (keys.get(i - 1).compareTo(keys.get(i)) > 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private void inOrder(Node node, ArrayList<K> keys) {
+        if (node == null) {
+            return;
+        }
+        inOrder(node.left, keys);
+        keys.add(node.key);
+        inOrder(node.right, keys);
+    }
+
+    // 判断该二叉树是否是一棵平衡二叉树
+    public boolean isBalanced() {
+        return isBalanced(root);
+    }
+
+    // 判断以Node节点为根的二叉树是否是一棵平衡二叉树，递归算法
+    private boolean isBalanced(Node node) {
+        if (node == null) {
+            return true;
+        }
+        int balanceFactor = getBalanceFactor(node);
+        if (Math.abs(balanceFactor) > 1) {
+            return false;
+        }
+        return isBalanced(node.left) && isBalanced(node.right);
+    }
+
+    private int getHeight(Node node) {
+        if (node == null)
+            return 0;
+        return node.height;
+    }
+
+    // 获得节点node的平衡因子
+    private int getBalanceFactor(Node node) {
+        if (node == null)
+            return 0;
+
+        return getHeight(node.left) - getHeight(node.right);
+    }
+
+    // 对节点y进行向右旋转操作，返回旋转后新的根节点x
+    private Node rightRotate(Node y) {
+        Node x = y.left;
+        Node T3 = x.right;
+
+        // 向右旋转过程
+        x.right = y;
+        y.left = T3;
+
+        // 更新 height （只需要更新 y和x， 先y后x）
+        y.height = Math.max(getHeight(y.left), getHeight(y.right)) + 1;
+        x.height = Math.max(getHeight(x.left), getHeight(x.right)) + 1;
+
+        return x;
+    }
+
+    // 对节点y进行向左旋转操作，返回旋转后新的根节点x
+    private Node leftRotate(Node y) {
+        Node x = y.right;
+        Node T2 = x.left;
+
+        // 向左旋转过程
+        x.left = y;
+        y.right = T2;
+
+        // 更新 height （只需要更新 y和x， 先y后x）
+        y.height = Math.max(getHeight(y.left), getHeight(y.right)) + 1;
+        x.height = Math.max(getHeight(x.left), getHeight(x.right)) + 1;
+
+        return x;
+    }
+
+    // 向二分搜索树中添加新的元素(key, value)
+    public void add(K key, V value) {
+        root = add(root, key, value);
+    }
+
+    // 向以node为根的二分搜索树中插入元素(key, value)，递归算法
+    // 返回插入新节点后二分搜索树的根
+    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 // key.compareTo(node.key) == 0
+            node.value = value;
+
+        // 更新 height
+        node.height = 1 + Math.max(getHeight(node.left), getHeight(node.right));
+
+        // 计算平衡因子
+        int balanceFactor = getBalanceFactor(node);
+//        if (Math.abs(balanceFactor) > 1) {
+//            System.out.println("unbabalanced : " + balanceFactor);
+//        }
+
+        // 平衡维护
+        // LL
+        if (balanceFactor > 1 && getBalanceFactor(node.left) >= 0) {
+            return rightRotate(node);
+        }
+        // RR
+        if (balanceFactor < -1 && getBalanceFactor(node.right) <= 0) {
+            return leftRotate(node);
+        }
+        // LR
+        if (balanceFactor > 1 && getBalanceFactor(node.left) < 0) {
+            node.left = leftRotate(node.left); // 转化成LL
+            return rightRotate(node);
+        }
+        // RL
+        if (balanceFactor < -1 && getBalanceFactor(node.right) > 0) {
+            node.right = rightRotate(node.right);// 转化成RR
+            return leftRotate(node);
+        }
+
+        return node;
+    }
+
+    // 返回以node为根节点的二分搜索树中，key所在的节点
+    private Node getNode(Node node, K key) {
+
+        if (node == null)
+            return null;
+
+        if (key.equals(node.key))
+            return node;
+        else if (key.compareTo(node.key) < 0)
+            return getNode(node.left, key);
+        else // if(key.compareTo(node.key) > 0)
+            return getNode(node.right, key);
+    }
+
+    public boolean contains(K key) {
+        return getNode(root, key) != null;
+    }
+
+    public V get(K key) {
+
+        Node node = getNode(root, key);
+        return node == null ? null : node.value;
+    }
+
+    public void set(K key, V newValue) {
+        Node node = getNode(root, key);
+        if (node == null)
+            throw new IllegalArgumentException(key + " doesn't exist!");
+
+        node.value = newValue;
+    }
+
+    // 返回以node为根的二分搜索树的最小值所在的节点
+    private Node minimum(Node node) {
+        if (node.left == null)
+            return node;
+        return minimum(node.left);
+    }
+
+    // 删除掉以node为根的二分搜索树中的最小节点
+    // 返回删除节点后新的二分搜索树的根
+    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;
+    }
+
+    // 从二分搜索树中删除键为key的节点
+    public V remove(K key) {
+
+        Node node = getNode(root, key);
+        if (node != null) {
+            root = remove(root, key);
+            return node.value;
+        }
+        return null;
+    }
+
+    private Node remove(Node node, K key) {
+
+        if (node == null)
+            return null;
+
+        Node retNode;
+        if (key.compareTo(node.key) < 0) {
+            node.left = remove(node.left, key);
+            retNode = node;
+        } else if (key.compareTo(node.key) > 0) {
+            node.right = remove(node.right, key);
+            retNode = node;
+        } else {   // key.compareTo(node.key) == 0
+
+            // 待删除节点左子树为空的情况
+            if (node.left == null) {
+                Node rightNode = node.right;
+                node.right = null;
+                size--;
+                retNode = rightNode;
+            }
+
+            // 待删除节点右子树为空的情况
+            else if (node.right == null) {
+                Node leftNode = node.left;
+                node.left = null;
+                size--;
+                retNode = leftNode;
+            } else {  // 待删除节点左右子树均不为空的情况
+
+                // 找到比待删除节点大的最小节点, 即待删除节点右子树的最小节点
+                // 用这个节点顶替待删除节点的位置
+                Node successor = minimum(node.right);
+//            successor.right = removeMin(node.right); // 注意平衡
+                successor.right = remove(node.right, successor.key); // 注意平衡
+                successor.left = node.left;
+
+                node.left = node.right = null;
+
+                retNode = successor;
+            }
+
+        }
+        if (retNode == null) // 注意空处理
+            return null;
+
+        // 更新 height
+        retNode.height = 1 + Math.max(getHeight(retNode.left), getHeight(retNode.right));
+
+        // 计算平衡因子
+        int balanceFactor = getBalanceFactor(retNode);
+//        if (Math.abs(balanceFactor) > 1) {
+//            System.out.println("unbabalanced : " + balanceFactor);
+//        }
+
+        // 平衡维护
+        // LL
+        if (balanceFactor > 1 && getBalanceFactor(retNode.left) >= 0) {
+            return rightRotate(retNode);
+        }
+        // RR
+        if (balanceFactor < -1 && getBalanceFactor(retNode.right) <= 0) {
+            return leftRotate(retNode);
+        }
+        // LR
+        if (balanceFactor > 1 && getBalanceFactor(retNode.left) < 0) {
+            retNode.left = leftRotate(retNode.left); // 转化成LL
+            return rightRotate(retNode);
+        }
+        // RL
+        if (balanceFactor < -1 && getBalanceFactor(retNode.right) > 0) {
+            retNode.right = rightRotate(retNode.right);// 转化成RR
+            return leftRotate(retNode);
+        }
+
+        return retNode;
+    }
+
+    public static void main(String[] args) {
+
+        System.out.println("Pride and Prejudice");
+
+        ArrayList<String> words = new ArrayList<>();
+        if (FileOperation.readFile("AVLTree/pride-and-prejudice.txt", words)) {
+            System.out.println("Total words: " + words.size());
+
+            AVLTree<String, Integer> map = new AVLTree<>();
+            for (String word : words) {
+                if (map.contains(word))
+                    map.set(word, map.get(word) + 1);
+                else
+                    map.add(word, 1);
+            }
+
+            System.out.println("Total different words: " + map.getSize());
+            System.out.println("Frequency of PRIDE: " + map.get("pride"));
+            System.out.println("Frequency of PREJUDICE: " + map.get("prejudice"));
+
+            System.out.println("is BST : " + map.isBST());
+            System.out.println("is isBalanced : " + map.isBalanced());
+
+            for (String word : words) {
+                map.remove(word);
+                if (!map.isBST() || !map.isBalanced())
+                    throw new RuntimeException("Error");
+            }
+        }
+
+        System.out.println();
+    }
+}