【数据结构+Java】Java实现二叉树的增查、先/中/后序遍历

Java实现二叉树的增查、先/中/后序遍历

github代码地址

package Tree;

import java.util.Scanner;
/**
* 节点
* @author wsz
* @date 2018年1月17日
*/
class TreeNode{
String data;
TreeNode left;
TreeNode right;
}
/**
* @author wsz
* @date 2018年1月17日
*/
public class TreeDemo {
static Scanner s = new Scanner(System.in);
static int SIZE = 30;

//初始化树
TreeNode intTree(){
TreeNode node = new TreeNode();
if(node != null) {
System.out.println("输入根节点数据:");
node.data = s.next();
node.left = null;
node.right = null;
}
return node;
}
/**
* 添加节点
* @param node 被添加节点的数
*/
void AddTreeNode(TreeNode node) {
TreeNode pnode,parent;
String data;
if((pnode = new TreeNode()) != null) {
System.out.println("输入二叉树节点数据:");
pnode.data = s.next();
pnode.left = null;
pnode.right = null;
System.out.println("输入父节点数据:");
data = s.next();
parent = findTreeNode(node,data);
if(parent == null)
System.out.println("没有找到父节点");

System.out.println("1:添加到左子树 2:添加到右子树");
int select = s.nextInt();
do {
switch(select) {
case 1 :
if(parent.left != null) {
System.out.println("左节点不为空");
}else {
parent.left = pnode;
}
break;
case 2 :
if(parent.right != null) {
System.out.println("右节点不为空");
}else {
parent.right = pnode;
}
break;
default :
System.out.println("参数无效");
}
}while(select != 1 && select !=2);
}
}

/**
* 查找树中某一节点
* @param node root树
* @param data 节点的数据
* @return
*/
TreeNode findTreeNode(TreeNode node,String data) {
TreeNode ptr;

if(node != null){
if(data.equals(node.data)) {
return node;
}else {
if((ptr = findTreeNode(node.left,data)) != null) {
return ptr;
}else if((ptr = findTreeNode(node.right,data)) != null) {
return ptr;
}
}
}
return null;
}

/**
* 获取当前节点的右节点
* @param node
* @return
*/
TreeNode treeRightNode(TreeNode node) {
if(node != null)
return node.right;
return null;
}

/**
* 获取当前节点的左节点
* @param node
* @return
*/
TreeNode treeLeftNode(TreeNode node) {
if(node != null)
return node.left;
return null;
}
/**
* 获取树的深度
* @param node root树
* @return
*/
int treeDeep(TreeNode node) {
int left,right;
if(node == null) {
return 0;
}else {
left  = treeDeep(node.left);
right = treeDeep(node.right);
if(left > right) {
return left+1;
}else {
return right+1;
}
}
}
/**
* 清空树
* @param node
*/
void clearTree(TreeNode node) {
if(node != null) {
clearTree(node.left);
clearTree(node.right);
node = null;
}
}

void showData(TreeNode node) {
System.out.print(nod
9eb4
e.data+" ");
}
//按层遍历
void levelTree(TreeNode node) {
TreeNode p ;
TreeNode[] q = new TreeNode[30];
int head=0,tail=0;
if(node != null) {
tail = (tail+1)%SIZE;
q[tail] = node;
}
while(head != tail) {
head = (head+1)%SIZE;
p = q[head];
showData(p);
if(p.left != null) {
tail =(tail+1)%SIZE;
q[tail] = p.left;
}
if(p.right != null) {
tail =(tail+1)%SIZE;
q[tail] = p.right;
}
}
}
//先序遍历
void firstTree(TreeNode node) {
if(node != null) {
showData(node);
firstTree(node.left);
firstTree(node.right);
}
}
//中序遍历
void secodeTree(TreeNode node) {
if(node != null) {
secodeTree(node.left);
showData(node);
secodeTree(node.right);
}
}
//后序遍历
void threeTree(TreeNode node) {
if(node != null) {
threeTree(node.left);
threeTree(node.right);
showData(node);
}
}

/**
* @param args
*/
public static void main(String[] args) {
TreeDemo td = new TreeDemo();
TreeNode root = td.intTree();
int select;
do {
System.out.println("0:退出 1添加子节点");
select = s.nextInt();
switch(select) {
case 1:
td.AddTreeNode(root);
break;
case 0:
break;
default:
;
}
}while(select != 0);

System.out.println("深度:"+td.treeDeep(root));
td.levelTree(root);
System.out.println("");
td.firstTree(root);
System.out.println("");
td.threeTree(root);
}

}