Update 03-AVLTree.js

Author: loiane

chapter08/03-AVLTree.js

@@ -0,0 +1,149 @@
+function AVLTree() {
+
+    var Node = function(key){
+        this.key = key;
+        this.left = null;
+        this.right = null;
+    };
+
+    var root = null;
+
+    this.getRoot = function(){
+        return root;
+    };
+
+    var heightNode = function(node) {
+        if (node === null) {
+            return -1;
+        } else {
+            return Math.max(heightNode(node.left), heightNode(node.right)) + 1;
+        }
+    };
+
+    var rotationLL = function(node) {
+        var tmp = node.left;
+        node.left = tmp.right;
+        tmp.right = node;
+
+        return tmp;
+    };
+
+    var rotationRR = function(node) {
+        var tmp = node.right;
+        node.right = tmp.left;
+        tmp.left = node;
+
+        return tmp;
+    };
+
+    var rotationLR = function(node) {
+        node.left = rotationRR(node.left);
+        return rotationLL(node);
+    };
+
+    var rotationRL = function(node) {
+        node.right = rotationLL(node.right);
+        return rotationRR(node);
+    };
+
+    var insertNode = function(node, element) {
+
+        if (node === null) {
+            node = new Node(element);
+
+        } else if (element < node.key) {
+
+            node.left = insertNode(node.left, element);
+
+            if (node.left !== null) {
+
+                if ((heightNode(node.left) - heightNode(node.right)) > 1){
+                    if (element < node.left.key){
+                        node = rotationLL(node);
+                    } else {
+                        node = rotationLR(node);
+                    }
+                }
+            }
+        } else if (element > node.key) {
+
+            node.right = insertNode(node.right, element);
+
+            if (node.right !== null) {
+
+                if ((heightNode(node.right) - heightNode(node.left)) > 1){
+
+                    if (element > node.right.key){
+                        node = rotationRR(node);
+                    } else {
+                        node = rotationRL(node);
+                    }
+                }
+            }
+        }
+
+        return node;
+    };
+
+    this.insert = function(element) {
+        root = insertNode(root, element);
+    };
+
+    var parentNode;
+    var nodeToBeDeleted;
+
+    var removeNode = function(node, element) {
+        if (node === null) {
+            return null;
+        }
+        parentNode = node;
+
+        if (element < node.key) {
+            node.left = removeNode(node.left, element);
+        } else {
+            nodeToBeDeleted = node;
+            node.right = removeNode(node.right, element);
+        }
+
+        if (node === parentNode) { //remove node
+            if (nodeToBeDeleted !== null && element === nodeToBeDeleted.key) {
+                if (nodeToBeDeleted === parentNode) {
+                    node = node.left;
+                } else {
+                    var tmp = nodeToBeDeleted.key;
+                    nodeToBeDeleted.key = parentNode.key;
+                    parentNode.key = tmp;
+                    node = node.right;
+                }
+            }
+        } else { //do balancing
+
+            if (node.left === undefined) node.left = null;
+            if (node.right === undefined) node.right = null;
+
+            if ((heightNode(node.left) - heightNode(node.right)) === 2) {
+                if (element < node.left.key) {
+                    node = rotationLR(node);
+                } else {
+                    node = rotationLL(node);
+                }
+            }
+
+            if ((heightNode(node.right) - heightNode(node.left)) === 2) {
+                if (element > node.right.key) {
+                    node = rotationRL(node);
+                } else {
+                    node = rotationRR(node);
+                }
+            }
+        }
+
+        return node;
+    };
+
+    this.remove = function(element) {
+        parentNode = null;
+        nodeToBeDeleted = null;
+        root = removeNode(root, element);
+    };
+}