package zz;import java.util.Stack;/*** 二叉树中的二叉搜索树，即一个节点的左子节点关键值小于这个节点，右子节点的关键值大于这个节点* * @author Administrator**/
class TreeNode {int value;TreeNode leftChild;TreeNode rightChild;public TreeNode(int value) {this.value = value;this.leftChild = null;this.rightChild = null;}
}public class Test {// 求二叉树的深度public static int getTreeLength(TreeNode root) {if (root == null)return 0;if (root.leftChild == null && root.rightChild == null)return 1;elsereturn 1 + Math.max(getTreeLength(root.leftChild), getTreeLength(root.rightChild));}// 插入子节点public static void insert(TreeNode root, int data) {TreeNode newNode = new TreeNode(data);if (root == null) {root = newNode;root.leftChild = null;root.rightChild = null;} else {TreeNode cur = root;TreeNode parent;while (true) {parent = cur;if (data <= cur.value) {cur = cur.leftChild;if (cur == null) {parent.leftChild = newNode;return;}} else {cur = cur.rightChild;if (cur == null) {parent.rightChild = newNode;return;}}}}}// 查找二叉搜索树中的某个节点public static TreeNode find(TreeNode root, int data) {TreeNode cur = root;while (data != cur.value) {if (data > cur.value) {cur = cur.rightChild;} else {cur = cur.leftChild;}if (cur == null)return null;}return cur;}// 先序遍历（递归实现）：先访问根节点，再访问左子节点，最后访问右孩子节点public static void recPreOrder(TreeNode root) {if (root == null)return;System.out.print(root.value + ",");if (root.leftChild != null)recPreOrder(root.leftChild);if (root.rightChild != null)recPreOrder(root.rightChild);}// 先序遍历（栈实现）：先访问根节点，再访问左子节点，最后访问右孩子节点public static void PreOrder(TreeNode root) {if (root == null)  return;Stack<TreeNode> stacks = new Stack<TreeNode>();TreeNode node = root;while (node != null || stacks.size() > 0) {while (node != null) {System.out.print(node.value + " ");stacks.push(node);node = node.leftChild;}if (stacks.size() > 0) {node = stacks.pop();//System.out.print(node.value + ",");node = node.rightChild;}}}// 中序遍历（递归实现）：先访问左子节点，再访问根节点，最后访问右子节点public static void recInOrder(TreeNode root) {if (root == null)return;if (root.leftChild != null)recInOrder(root.leftChild);System.out.print(root.value + ",");if (root.rightChild != null)recInOrder(root.rightChild);}//中序遍历（栈实现）：先访问左子节点，再访问根节点，最后访问右子节点public static void InOrder(TreeNode root) {if(root == null)  return;Stack<TreeNode> stacks = new Stack<TreeNode>();TreeNode node = root;while(node != null || stacks.size() > 0) {while(node != null) {stacks.push(node);node = node.leftChild;}if(!stacks.isEmpty()) {node = stacks.pop();System.out.print(node.value + " ");node = node.rightChild;}}}// 后序遍历（递归实现）：先访问左子节点，再访问右子节点，最后访问根节点public static void recPostOrder(TreeNode root) {if (root == null)return;if (root.leftChild != null)recInOrder(root.leftChild);if (root.rightChild != null)recInOrder(root.rightChild);System.out.print(root.value + ",");}// 后序遍历(栈实现）：先访问左子节点，再访问右子节点，最后访问根节点public static void PostOrder(TreeNode root) {if(root == null)  return;Stack<TreeNode> stacks = new Stack<TreeNode>();TreeNode node = root;TreeNode preNode = null;while(node != null || !stacks.isEmpty()) {while(node != null) {stacks.push(node);node = node.leftChild;}node = stacks.peek();if(node.rightChild == null || node.rightChild == preNode) {System.out.print(node.value + " ");node = stacks.pop();preNode = node;node = null;} else {node = node.rightChild;}}}public static void main(String[] args) {TreeNode root = new TreeNode(4);insert(root, 2);insert(root, 6);insert(root, 1);insert(root, 3);insert(root, 5);insert(root, 7);insert(root, 8);System.out.println("非递归先序遍历树：");PreOrder(root);System.out.println();System.out.println("非递归中序遍历树");InOrder(root);System.out.println();System.out.println("非递归后序遍历树");PostOrder(root);}
}