Java实现二叉树的基本操作

更多例题：http://blog.csdn.net/lhfight/article/details/7789527

 

package D0726;import java.util.ArrayDeque;import java.util.Queue;public class TestTree {public static void main(String[] args) {// 测试TreenodeTreenode node = buildTree(null, 1);System.out.print("先序遍历：");preOrder(node);System.out.println();System.out.print("中序遍历：");inOrder(node);System.out.println();System.out.print("后序遍历：");postOrder(node);System.out.println();System.out.print("层次遍历：");levelOrder(node);System.out.println();System.out.print("叶子节点数目：");System.out.println(leafNum(node));System.out.print("二叉树的深度：");System.out.println(deep(node));}// 建立树@k用来控制树的深度static char i = 'a';// 节点public static Treenode buildTree(Treenode node, int k) {if (k > 4)return null;if (node == null) {node = new Treenode(" " + i++);}node.lChild = buildTree(node.lChild, k + 1);node.rChild = buildTree(node.rChild, k + 1);return node;}// 根据先序和中序来构建二叉树public Treenode buildTree(String pre, String in) {if (pre.length() <= 0)return null;Treenode root = new Treenode(pre.charAt(0) + "");// 以根节点为中心，将中序分为两个子序列String leftin = "";String rightin = "";// 根所左中序的长度，将先序分为左右两个子先序String leftpre = "";String rightpre = "";root.lChild = buildTree(leftpre, leftin);root.rChild = buildTree(rightpre, rightin);return root;}// 先序遍历public static void preOrder(Treenode node) {if (node != null) {System.out.print(node.data);preOrder(node.lChild);preOrder(node.rChild);}}// 中序遍历public static void inOrder(Treenode node) {if (node != null) {inOrder(node.lChild);System.out.print(node.data);inOrder(node.rChild);}}// 后序遍历public static void postOrder(Treenode node) {if (node != null) {postOrder(node.lChild);postOrder(node.rChild);System.out.print(node.data);}}// 层次遍历public static void levelOrder(Treenode node) {if (node == null)return;Queue<Treenode> queue = new ArrayDeque<Treenode>();queue.add(node);while (!queue.isEmpty()) {Treenode temp = queue.poll();System.out.print(temp.data);if (temp.lChild != null)queue.add(temp.lChild);if (temp.rChild != null)queue.add(temp.rChild);}}// 求树的叶子节点数public static int leafNum(Treenode node) {if (node != null) {if (node.lChild == null && node.rChild == null) {return 1;}return leafNum(node.lChild)+leafNum(node.rChild);}return 0;}//求二叉树的深度public static int deep(Treenode node){if(node == null)return 0;if(node.lChild==null&&node.rChild==null)return 1;return leafNum(node.lChild)+leafNum(node.rChild);}}class Treenode {public String data;public Treenode lChild;public Treenode rChild;// 构造函数public Treenode(String data) {this.data = data;this.lChild = null;this.rChild = null;}}