手写一个java实现二叉树的算法以及用先序、中序、后序以及层序遍历二叉树的方法
package Tree;
import java.util.LinkedList;
import java.util.Queue;
class Node {
public int data;
public Node left;
public Node right;
public Node(int data){
this.data = data;
this.left = null;
this.right = null;
}
}
public class BinaryTree{
private Node root;
public BinaryTree(){
root = null;
}
//将data插入到排序二叉树中
public void insert(int data){
Node newNode = new Node(data);
if(root==null){
root=newNode;
}else{
Node parent = root;
Node current = root;
while(true){
current = parent;
if(data<current.data){
current = current.left;
if(current==null){
parent.left = newNode;
}
}else{
current = current.right;
if(current==null){
parent.right = newNode;
}
}
}
}
}
//将树枝输入构建二叉树
public void buildTree(int[] data){
for(int i=0;i<data.length;i++){
insert(data[i]);
}
}
//中序遍历方法递归实现
public void inOrder(Node localRoot){
if(localRoot!=null){
inOrder(localRoot.left);
System.out.println(localRoot.data+" ");
inOrder(localRoot.right);
}
}
public void inOrder(){
this.inOrder(this.root);
}
//先序遍历方法递归实现
public void preOrder(Node localRoot){
if(localRoot!=null){
System.out.println(localRoot.data);
preOrder(localRoot.left);
preOrder(localRoot.right);
}
}
public void preOrder(){
this.preOrder(this.root);
}
//后序遍历方法递归实现
public void postOrder(Node localRoot){
if(localRoot!=null){
postOrder(localRoot.left);
postOrder(localRoot.right);
System.out.println(localRoot.data);
}
}
public void postOrder(){
this.postOrder(this.root);
}
//使用队列层序遍历二叉树
public void layerTranverse(){
if(this.root == null){
return;
}else{
Queue<Node> q = new LinkedList<Node>();
q.add(this.root);
while(!q.isEmpty()){
Node n = q.poll();
System.out.print(n.data+" ");
if(n.left!=null){
q.offer(n.left);
}
if(n.right!=null){
q.offer(n.right);
}
}
}
}
public static void main(String[] args){
BinaryTree biTree = new BinaryTree();
int[] data = {2,8,7,4,9,3,1,6,7,5};
biTree.buildTree(data);
System.out.print("二叉树的中序遍历:");
biTree.inOrder();
System.out.println();
System.out.print("二叉树的先序遍历:");
biTree.preOrder();
System.out.println();
System.out.print("二叉树的后序遍历:");
biTree.postOrder();
System.out.println();
System.out.print("二叉树的层序遍历:");
biTree.layerTranverse();
}
}