package treeDemo;/*** Created by chengxiao on 2017/02/12.*/
public class BinaryTree {//根节点private Node root;/*** 树的结点*/private static class Node{//数据域private long data;//左子结点private Node leftChild;//右子结点private Node rightChild;Node(long data){this.data = data;}}/*** 插入结点* @param data*/public void insert(long data){Node newNode = new Node(data);Node currNode = root;Node parentNode;//如果是空树if(root == null){root = newNode;return;}while(true){parentNode = currNode;//向右搜寻if(data > currNode.data){currNode = currNode.rightChild;if(currNode == null){parentNode.rightChild = newNode;return;}}else{//向左搜寻currNode = currNode.leftChild;if(currNode == null){parentNode.leftChild = newNode;return;}}}}/*** 前序遍历* @param currNode*/public void preOrder(Node currNode){if(currNode == null){return;}System.out.print(currNode.data+" ");preOrder(currNode.leftChild);preOrder(currNode.rightChild);}/*** 中序遍历* @param currNode*/public void inOrder(Node currNode){if(currNode == null){return;}inOrder(currNode.leftChild);System.out.print(currNode.data+" ");inOrder(currNode.rightChild);}/*** 后序遍历* @param currNode*/public void postOrder(Node currNode){if(currNode == null){return;}postOrder(currNode.leftChild);postOrder(currNode.rightChild);System.out.print(currNode.data+" ");}/*** 查找结点* @param data* @return*/public Node find(long data){Node currNode = root;while(currNode!=null){if(data>currNode.data){currNode = currNode.rightChild;}else if(data<currNode.data){currNode = currNode.leftChild;}else{return currNode;}}return null;}/*** 删除结点 分为3种情况* 1.叶子结点* 2.该节点有一个子节点* 3.该节点有二个子节点* @param data*/public boolean delete(long data) throws Exception {Node curr = root;//保持一个父节点的引用Node parent = curr;//删除结点是左子结点还是右子结点，boolean isLeft = true;while(curr != null && curr.data!=data){parent = curr;if(data > curr.data){curr = curr.rightChild;isLeft = false;}else{curr = curr.leftChild;isLeft = true;}}if(curr==null){throw new Exception("要删除的结点不存在");}//第一种情况,要删除的结点为叶子结点if(curr.leftChild == null && curr.rightChild == null){if(curr == root){root = null;return true;}if(isLeft){parent.leftChild = null;}else{parent.rightChild = null;}}else if(curr.leftChild == null){//第二种情况，要删除的结点有一个子节点且是右子结点if(curr == root){root = curr.rightChild;return true;}if(isLeft){parent.leftChild = curr.rightChild;}else{parent.rightChild = curr.rightChild;}}else if(curr.rightChild == null){//第二种情况，要删除的结点有一个子节点且是左子结点if(curr == root){root = curr.leftChild;return true;}if(isLeft){parent.leftChild = curr.leftChild;}else{parent.rightChild = curr.leftChild;}}else{//第三种情况，也是最复杂的一种情况，要删除的结点有两个子节点，需要找寻中序后继结点Node succeeder = getSucceeder(curr);if(curr == root){root = succeeder;return  true;}if(isLeft){parent.leftChild = succeeder;}else{parent.rightChild = succeeder;}//当后继结点为删除结点的右子结点succeeder.leftChild = curr.leftChild;}return true;}public Node getSucceeder(Node delNode){Node succeeder = delNode;Node parent = delNode;Node currNode = delNode.rightChild;//寻找后继结点while(currNode != null){parent = succeeder;succeeder = currNode;currNode = currNode.leftChild;}//如果后继结点不是要删除结点的右子结点if(succeeder != delNode.rightChild){parent.leftChild = succeeder.rightChild;//将后继结点的左右子结点分别指向要删除结点的左右子节点succeeder.leftChild = delNode.leftChild;succeeder.rightChild = delNode.rightChild;}return succeeder;}public static void main(String []args) throws Exception {BinaryTree binaryTree = new BinaryTree();//插入操作binaryTree.insert(5);binaryTree.insert(2);binaryTree.insert(8);binaryTree.insert(1);binaryTree.insert(3);binaryTree.insert(6);binaryTree.insert(10);//前序遍历System.out.println("前序遍历：");binaryTree.preOrder(binaryTree.root);System.out.println();//中序遍历System.out.println("中序遍历：");binaryTree.inOrder(binaryTree.root);System.out.println();//后序遍历System.out.println("后序遍历：");binaryTree.postOrder(binaryTree.root);System.out.println();//查找结点Node node = binaryTree.find(10);System.out.println("找到结点，其值为："+node.data);//删除结点binaryTree.delete(8);System.out.print("删除结点8,中序遍历：");binaryTree.preOrder(binaryTree.root);}
}二叉树的基本操作