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Copy pathConstructBinaryTree.java
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257 lines (243 loc) · 5.29 KB
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package com.wg.offerAlgorithm;
import java.util.Stack;
/*
* 重建二叉树
* 二叉树的创建，遍历
*
*/
public class ConstructBinaryTree {
private Node root;
private class Node{
private int data;
private Node left;
private Node right;
public Node(int data){
this.data=data;
this.left=null;
this.right=null;
}
}
public ConstructBinaryTree(){
root=null;
}
//递归构建树
public void buildTree(Node node,int data){
if( root==null){
root=new Node(data);
}else{
if(data<node.data){
if(node.left==null){
node.left=new Node(data);
}else{
buildTree(node.left,data);
}
}if(data>node.data){
if(node.right==null){
node.right=new Node(data);
}else{
buildTree(node.right,data);
}
}
}
}
/**
* 前序遍历
* @param node
*/
public void preOrder(Node node){
if(node != null){
System.out.print(node.data+" ");
preOrder(node.left);
preOrder(node.right);
}
}
/**
* 非递归二叉树前序遍历
* 利用栈实现
* @param node
*/
public void preOrder_(Node node){
Stack<Node> stack = new Stack<Node>();
if(node!=null){
stack.push(node);
while(!stack.empty()){
node=stack.pop();
System.out.print(node.data+" ");
if(node.right!=null){
stack.push(node.right);
}
if(node.left!=null){
stack.push(node.left);
}
}
}
}
/**
* 中序遍历
* @param node
*/
public void inOrder(Node node){
if(node != null){
inOrder(node.left);
System.out.print(node.data+" ");
inOrder(node.right);
}
}
/**
* 中序非递归遍历
* @param node
*/
public void inOrder_(Node node){
Stack<Node> stack = new Stack<Node>();
while(node!=null ||stack.size()>0){
while(node!=null){
stack.push(node);
node=node.left;
}
if(stack.size()>0){
node=stack.pop();
System.out.print(node.data+" ");
node = node.right;
}
}
}
public void in_Order(Node node){
Stack<Node> stack = new Stack<Node>();
while(node!=null||stack.size()>0){
while(node!=null){
//根元素压栈
stack.push(node);
node=node.left;
}
if(stack.size()>0){
//出栈
node=stack.pop();
System.out.println(node.data);
node=node.right;
}
}
}
/**
* 后序遍历
* @param node
*/
public void postOrder(Node node){
if(node != null){
postOrder(node.left);
postOrder(node.right);
System.out.print(node.data+" ");
}
}
/**
* 后续非递归遍历
* @param node
*/
public void postOrder_(Node node){
Stack<Node> stack = new Stack<Node>();
Node prve=node;
while(node!=null||stack.size()>0){
while(node!=null){
stack.push(node);
node = node.left;
}
if(stack.size()>0){
Node temp = stack.peek().right;
if(temp==null||temp==prve){
node = stack.pop();
System.out.print(node.data+" ");
prve =node;
node=null;
}else{
node = temp;
}
}
}
}
/**
* 二叉树插入节点
* @param data
*/
public void insert(int data){
Node newNode = new Node(data);
if(root==null){
root = newNode;
}
else{
Node current=root;
Node parent;
while(true){
parent=current;
//左子树
if(current.data>data){
current=current.left;
if(current==null){
parent.left=newNode;
return;
}
}
else{
current =current.right;
if(current==null){
parent.right=newNode;
return;
}
}
System.out.println(parent.data);
}
}
}
/**
* 查找最小值
* @param root
* @return
*/
public Node minimum(Node root){
Node last=null;
Node current= root;
while(current!=null){
last=current;
current = current.left;
}
return last;
}
/**
* 查找最大值
* @param root
* @return
*/
public Node maxmum(Node root){
Node last=null;
Node current=root;
while(current!=null){
last=current;
current=current.right;
}
return last;
}
/**
* 删除节点
* @param node
*/
public void deleteNode(Node node){
}
public static void main(String[] args) {
// TODO Auto-generated method stub
// int[] a = {2,4,12,45,21,6,111};
int[] a={12,76,35,22,16,48,90,46,9,40};
ConstructBinaryTree bTree = new ConstructBinaryTree();
for (int i = 0; i < a.length; i++) {
bTree.buildTree(bTree.root, a[i]);
}
// bTree.insert(20);
// Node last=bTree.minimum(bTree.root);
// System.out.println(last.data);
// bTree.preOrder_(bTree.root);
// System.out.println();
bTree.in_Order(bTree.root);
System.out.println();
// bTree.inOrder(bTree.root);
// System.out.println();
// bTree.postOrder_(bTree.root);
}
}
//