translation: Add Python and Java code for EN version (#1345)

* Add the intial translation of code of all the languages

* test

* revert

* Remove

* Add Python and Java code for EN version

en/codes/java/chapter_tree/avl_tree.java

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+/**
+ * File: avl_tree.java
+ * Created Time: 2022-12-10
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_tree;
+
+import utils.*;
+
+/* AVL tree */
+class AVLTree {
+    TreeNode root; // Root node
+
+    /* Get node height */
+    public int height(TreeNode node) {
+        // Empty node height is -1, leaf node height is 0
+        return node == null ? -1 : node.height;
+    }
+
+    /* Update node height */
+    private void updateHeight(TreeNode node) {
+        // Node height equals the height of the tallest subtree + 1
+        node.height = Math.max(height(node.left), height(node.right)) + 1;
+    }
+
+    /* Get balance factor */
+    public int balanceFactor(TreeNode node) {
+        // Empty node balance factor is 0
+        if (node == null)
+            return 0;
+        // Node balance factor = left subtree height - right subtree height
+        return height(node.left) - height(node.right);
+    }
+
+    /* Right rotation operation */
+    private TreeNode rightRotate(TreeNode node) {
+        TreeNode child = node.left;
+        TreeNode grandChild = child.right;
+        // Rotate node to the right around child
+        child.right = node;
+        node.left = grandChild;
+        // Update node height
+        updateHeight(node);
+        updateHeight(child);
+        // Return the root of the subtree after rotation
+        return child;
+    }
+
+    /* Left rotation operation */
+    private TreeNode leftRotate(TreeNode node) {
+        TreeNode child = node.right;
+        TreeNode grandChild = child.left;
+        // Rotate node to the left around child
+        child.left = node;
+        node.right = grandChild;
+        // Update node height
+        updateHeight(node);
+        updateHeight(child);
+        // Return the root of the subtree after rotation
+        return child;
+    }
+
+    /* Perform rotation operation to restore balance to the subtree */
+    private TreeNode rotate(TreeNode node) {
+        // Get the balance factor of node
+        int balanceFactor = balanceFactor(node);
+        // Left-leaning tree
+        if (balanceFactor > 1) {
+            if (balanceFactor(node.left) >= 0) {
+                // Right rotation
+                return rightRotate(node);
+            } else {
+                // First left rotation then right rotation
+                node.left = leftRotate(node.left);
+                return rightRotate(node);
+            }
+        }
+        // Right-leaning tree
+        if (balanceFactor < -1) {
+            if (balanceFactor(node.right) <= 0) {
+                // Left rotation
+                return leftRotate(node);
+            } else {
+                // First right rotation then left rotation
+                node.right = rightRotate(node.right);
+                return leftRotate(node);
+            }
+        }
+        // Balanced tree, no rotation needed, return
+        return node;
+    }
+
+    /* Insert node */
+    public void insert(int val) {
+        root = insertHelper(root, val);
+    }
+
+    /* Recursively insert node (helper method) */
+    private TreeNode insertHelper(TreeNode node, int val) {
+        if (node == null)
+            return new TreeNode(val);
+        /* 1. Find insertion position and insert node */
+        if (val < node.val)
+            node.left = insertHelper(node.left, val);
+        else if (val > node.val)
+            node.right = insertHelper(node.right, val);
+        else
+            return node; // Do not insert duplicate nodes, return
+        updateHeight(node); // Update node height
+        /* 2. Perform rotation operation to restore balance to the subtree */
+        node = rotate(node);
+        // Return the root node of the subtree
+        return node;
+    }
+
+    /* Remove node */
+    public void remove(int val) {
+        root = removeHelper(root, val);
+    }
+
+    /* Recursively remove node (helper method) */
+    private TreeNode removeHelper(TreeNode node, int val) {
+        if (node == null)
+            return null;
+        /* 1. Find and remove the node */
+        if (val < node.val)
+            node.left = removeHelper(node.left, val);
+        else if (val > node.val)
+            node.right = removeHelper(node.right, val);
+        else {
+            if (node.left == null || node.right == null) {
+                TreeNode child = node.left != null ? node.left : node.right;
+                // Number of child nodes = 0, remove node and return
+                if (child == null)
+                    return null;
+                // Number of child nodes = 1, remove node
+                else
+                    node = child;
+            } else {
+                // Number of child nodes = 2, remove the next node in in-order traversal and replace the current node with it
+                TreeNode temp = node.right;
+                while (temp.left != null) {
+                    temp = temp.left;
+                }
+                node.right = removeHelper(node.right, temp.val);
+                node.val = temp.val;
+            }
+        }
+        updateHeight(node); // Update node height
+        /* 2. Perform rotation operation to restore balance to the subtree */
+        node = rotate(node);
+        // Return the root node of the subtree
+        return node;
+    }
+
+    /* Search node */
+    public TreeNode search(int val) {
+        TreeNode cur = root;
+        // Loop find, break after passing leaf nodes
+        while (cur != null) {
+            // Target node is in cur's right subtree
+            if (cur.val < val)
+                cur = cur.right;
+            // Target node is in cur's left subtree
+            else if (cur.val > val)
+                cur = cur.left;
+            // Found target node, break loop
+            else
+                break;
+        }
+        // Return target node
+        return cur;
+    }
+}
+
+public class avl_tree {
+    static void testInsert(AVLTree tree, int val) {
+        tree.insert(val);
+        System.out.println("\nAfter inserting node " + val + ", the AVL tree is ");
+        PrintUtil.printTree(tree.root);
+    }
+
+    static void testRemove(AVLTree tree, int val) {
+        tree.remove(val);
+        System.out.println("\nAfter removing node " + val + ", the AVL tree is ");
+        PrintUtil.printTree(tree.root);
+    }
+
+    public static void main(String[] args) {
+        /* Initialize empty AVL tree */
+        AVLTree avlTree = new AVLTree();
+
+        /* Insert node */
+        // Notice how the AVL tree maintains balance after inserting nodes
+        testInsert(avlTree, 1);
+        testInsert(avlTree, 2);
+        testInsert(avlTree, 3);
+        testInsert(avlTree, 4);
+        testInsert(avlTree, 5);
+        testInsert(avlTree, 8);
+        testInsert(avlTree, 7);
+        testInsert(avlTree, 9);
+        testInsert(avlTree, 10);
+        testInsert(avlTree, 6);
+
+        /* Insert duplicate node */
+        testInsert(avlTree, 7);
+
+        /* Remove node */
+        // Notice how the AVL tree maintains balance after removing nodes
+        testRemove(avlTree, 8); // Remove node with degree 0
+        testRemove(avlTree, 5); // Remove node with degree 1
+        testRemove(avlTree, 4); // Remove node with degree 2
+
+        /* Search node */
+        TreeNode node = avlTree.search(7);
+        System.out.println("\nThe found node object is " + node + ", node value = " + node.val);
+    }
+}