AVL树

public class AVLTree {public static class AVLTreeNode {AVLTreeNode mLeftNode;AVLTreeNode mRightNode;AVLTreeNode mParent;public int mHeight;int mValue;public AVLTreeNode() {mLeftNode = null;mRightNode = null;mParent = null;mHeight = 0;}public AVLTreeNode(int value) {this();mValue = value;}}public static int getNodeHeight(AVLTreeNode node) {return node == null ? -1 : node.mHeight;}private AVLTreeNode mHeader;public AVLTreeNode find(int value) {AVLTreeNode node = mHeader;return findNode(node, value);}private AVLTreeNode findNode(AVLTreeNode startNode, int value) {AVLTreeNode node = startNode;while (null != node) {if (node.mValue == value) {return node;} else if (value > node.mValue) {node = node.mRightNode;} else {node = node.mLeftNode;}}return null;}public void printLevel() {System.out.println("=======================================");printLevelNode(mHeader, 0);System.out.println("=======================================");}private void printLevelNode(AVLTreeNode node, int level) {if (null != node) {for (int i = 0; i < level; i++) {System.out.print("    ");}System.out.println(String.valueOf(node.mValue));printLevelNode(node.mLeftNode, level + 1);printLevelNode(node.mRightNode, level + 1);}}public void print() {printNode(mHeader);}private void printNode(AVLTreeNode node) {if (null != node) {printNode(node.mLeftNode);System.out.print("     " + node.mValue);printNode(node.mRightNode);}}public int findMin() {if (null == mHeader) {throw new IllegalStateException("树为空");}AVLTreeNode node = findMinNode(mHeader);return node.mValue;}private AVLTreeNode findMinNode(AVLTreeNode startNode) {AVLTreeNode node = startNode;while (null != node.mLeftNode) node = node.mLeftNode;return node;}public int findMax() {if (null == mHeader) {throw new IllegalStateException("树为空");}AVLTreeNode node = findMaxNode(mHeader);return node.mValue;}private AVLTreeNode findMaxNode(AVLTreeNode startNode) {AVLTreeNode node = startNode;while (null != node.mRightNode) node = node.mRightNode;return node;}// 插入：public void insert(int value) {insert(mHeader, mHeader, value);}private void insert(AVLTreeNode targetParent, AVLTreeNode target, int value) {if (target == null) { // 当前节点已经是空节点了，也就是必须在这里插入了target = new AVLTreeNode();target.mValue = value;if (null == targetParent) {// 这才说明是空树mHeader = target;} else {target.mParent = targetParent;if (targetParent.mValue > value) {targetParent.mLeftNode = target;} else {targetParent.mRightNode = target;}}return;} else if (target.mValue > value) {// 递归插入：在左边插入，只会改变左子树的高度insert(target, target.mLeftNode, value);// 向左侧插入，只能左侧比右侧大if (getNodeHeight(target.mLeftNode) - getNodeHeight(target.mRightNode) >= 2) {if (target.mLeftNode.mValue > value) { // LLrightRotate(target);} else {// LRleftRightRotate(target);}}} else if (target.mValue < value) {insert(target, target.mRightNode, value);if (getNodeHeight(target.mRightNode) - getNodeHeight(target.mLeftNode) >= 2) {if (target.mRightNode.mValue < value) {  // RRleftRotate(target);} else {// RLrightLeftRotate(target);}}} else { // 已经存在了return;}// 重新计算高度：int leftHeight = getNodeHeight(target.mLeftNode);int rightHeight = getNodeHeight(target.mRightNode);target.mHeight = Math.max(leftHeight, rightHeight) + 1;}public void deleteNode(int value) {AVLTreeNode delNode = findNode(mHeader, value);if (null != delNode) {deleteNode(mHeader, value);} else {System.out.println("can not find node");}}public void deleteNode(AVLTreeNode target, int value) {if (target.mValue > value) {deleteNode(target.mLeftNode, value);} else if (target.mValue < value) {deleteNode(target.mRightNode, value);} else if (null != target.mLeftNode) {// 就是本尊：从左边替换// 替换target.mValue = findMaxNode(target.mLeftNode).mValue;deleteNode(target.mLeftNode, target.mValue);} else if (null != target.mRightNode) {// 就是本尊：从右边替换target.mValue = findMinNode(target.mRightNode).mValue;deleteNode(target.mRightNode, target.mValue);} else {// 没有孩子：直接删除if (target.mParent.mLeftNode == target) { // 做孩子target.mParent.mLeftNode = null;} else {target.mParent.mRightNode = null;}return;}int leftHeight = getNodeHeight(target.mLeftNode);int rightHeight = getNodeHeight(target.mRightNode);target.mHeight = Math.max(leftHeight, rightHeight) + 1;if (rightHeight - leftHeight >= 2) {if (target.mRightNode.mRightNode == null) {rightLeftRotate(target);} else {leftRotate(target);}} else if (leftHeight - rightHeight >= 2) {if (null == target.mLeftNode.mLeftNode) {leftRightRotate(target);} else {rightRotate(target);}}}/** * 左旋转 * @param target 目标 */private void leftRotate(AVLTreeNode target) {AVLTreeNode rightChild = target.mRightNode;// 处理右子树的左节点target.mRightNode = rightChild.mLeftNode;if (null != rightChild.mLeftNode) {rightChild.mLeftNode.mParent = target;}// 处理父节点if (target.mParent == null) { // 没有父节点mHeader = rightChild;rightChild.mParent = null;} else if (target.mParent.mLeftNode == target) { // 该子树在父节点的左子树上target.mParent.mLeftNode = rightChild;rightChild.mParent = target.mParent;} else { // 该子树在父节点的右子树上target.mParent.mRightNode = rightChild;rightChild.mParent = target.mParent;}// 颠倒父子关系rightChild.mLeftNode = target;target.mParent = rightChild;// 计算高度：int leftHeight = getNodeHeight(target.mLeftNode);int rightHeight = getNodeHeight(target.mRightNode);target.mHeight = Math.max(leftHeight, rightHeight) + 1;// rightChild已经是父节点了leftHeight = getNodeHeight(rightChild.mLeftNode);rightHeight = getNodeHeight(rightChild.mRightNode);rightChild.mHeight = Math.max(leftHeight, rightHeight) + 1;}private void rightRotate(AVLTreeNode target) {AVLTreeNode leftChild = target.mLeftNode;// 处理左子树的右节点target.mLeftNode = leftChild.mRightNode;if (null != leftChild.mRightNode) {leftChild.mRightNode.mParent = target;}// 处理父节点：if (null == target.mParent) {// 本身就是根mHeader = leftChild;leftChild.mParent = null;} else if (target.mParent.mLeftNode == target) {target.mParent.mLeftNode = leftChild;leftChild.mParent = target.mParent;} else {target.mParent.mRightNode = leftChild;leftChild.mParent = target.mParent;}// 颠倒父子关系：leftChild.mRightNode = target;target.mParent = leftChild;// 计算target的高度int leftHeight = getNodeHeight(target.mLeftNode);int rightHeight = getNodeHeight(target.mRightNode);target.mHeight = Math.max(leftHeight, rightHeight) + 1;// 计算leftChild(现在的父节点)leftHeight = getNodeHeight(leftChild.mLeftNode);rightHeight = getNodeHeight(leftChild.mRightNode);leftChild.mHeight = Math.max(leftHeight, rightHeight) + 1;}private void leftRightRotate(AVLTreeNode target) {leftRotate(target.mLeftNode);rightRotate(target);}private void rightLeftRotate(AVLTreeNode target) {rightRotate(target.mRightNode);leftRotate(target);}public static void main(String[] args) {AVLTree tree = new AVLTree();Random r = new Random(10);int length = 10;int value = 0;for (int i = 0; i < length; i++) {value = r.nextInt(1000);tree.insert(value);}tree.print();AVLTreeNode node = tree.find(value);if (null != node) {System.out.println("\nFind Value: " + node.mValue);// 把value到跟依次打印出来：System.out.println("从node到根的路径：");while (node != null) {System.out.print("     " + node.mValue);node = node.mParent;}} else {System.out.println("\nCANNOT Find Value: " + value);}int maxValue = tree.findMax();int minValue = tree.findMin();System.out.println("\n最大值：" + maxValue + ", 最小值：" + minValue);tree.printLevel();tree.deleteNode(293);tree.printLevel();}}