代码实现[一]部分
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package ChapterEight;
class Tree {
class Node {
public long value;
public Node leftChild;
public Node rightChild;
public Node(long value) {
this.value = value;
leftChild = null;
rightChild = null;
}
}
public Node root;
public Tree() {
root = null;
}
// 向树中插入一个节点
public void insert(long value) {
Node newNode = new Node(value);
// 树是空的
if (root == null)
root = newNode;
else {
Node current = root;
Node parentNode;
while (true) {
parentNode = current;
if (value current.value) {
current = current.leftChild;
// 要插入的节点为左孩子节点
if (current == null) {
parentNode.leftChild = newNode;
return;
}
} else {
// 要插入的节点为右孩子节点
current = current.rightChild;
if (current == null) {
parentNode.rightChild = newNode;
return;
}
}
}
}
}
// 先续遍历树中的所有节点
public void preOrder(Node currentRoot) {
if (currentRoot != null) {
System.out.print(currentRoot.value + " ");
preOrder(currentRoot.leftChild);
preOrder(currentRoot.rightChild);
}
}
// 中续遍历树中的所有节点
public void inOrder(Node currentNode) {
if (currentNode != null) {
inOrder(currentNode.leftChild);
System.out.print(currentNode.value + " ");
inOrder(currentNode.rightChild);
}
}
// 后续遍历树中的所有节点
public void postOrder(Node currentNode) {
if (currentNode != null) {
postOrder(currentNode.leftChild);
postOrder(currentNode.rightChild);
System.out.print(currentNode.value + " ");
}
}
public void traverse(int traverseType) {
switch (traverseType) {
case 1:
preOrder(root);
break;
case 2:
inOrder(root);
break;
case 3:
postOrder(root);
break;
default:
break;
}
// 依据树节点的值删除树中的一个节点
public boolean delete(int value) {
// 遍历树过程中的当前节点
Node current = root;
// 要删除节点的父节点
Node parent = root;
// 记录树的节点为左孩子节点或右孩子节点
boolean isLeftChild = true;
while (current.value != value) {
parent = current;
// 要删除的节点在当前节点的左子树里
if (value current.value) {
isLeftChild = true;
current = current.leftChild;
}
// 要删除的节点在当前节点的右子树里
else {
isLeftChild = false;
current = current.rightChild;
}
// 在树中没有找到要删除的节点
if (current == null)
return false;
}
// 要删除的节点为叶子节点
if (current.leftChild == null current.rightChild == null) {
// 要删除的节点为根节点
if (current == root)
root = null;
// 要删除的节点为左孩子节点
else if (isLeftChild)
parent.leftChild = null;
// 要删除的节点为右孩子节点
else
parent.rightChild = null;
}
// 要删除的节点有左孩子节点，没有右孩子节点
else if (current.rightChild == null) {
// 要删除的节点为根节点
if (current == null)
root = current.leftChild;
// 要删除的节点为左孩子节点
else if (isLeftChild)
parent.leftChild = current.leftChild;
// 要删除的节点为右孩子节点
else
parent.rightChild = current.leftChild;
}
// 要删除的节点没有左孩子节点，有右孩子节点
else if (current.leftChild == null) {
// 要删除的节点为根节点
if (current == root)
root = root.rightChild;
// 要删除的节点为左孩子节点
else if (isLeftChild)
parent.leftChild = current.rightChild;
// 要删除的节点为右孩子节点
else
parent.rightChild = current.rightChild;
}
// 要删除的接节点既有左孩子节点又有右孩子节点
else {
Node successor = getSuccessor(current);
// 要删除的节点为根节点
if (current == root)
root = successor;
// 要删除的节点为左孩子节点
else if (isLeftChild)
parent.leftChild = successor;
// 要删除的节点为右孩子节点
else
parent.rightChild = successor;
}
return true;
}
// 找到要删除节点的替补节点
private Node getSuccessor(Node delNode) {
// 替补节点的父节点
Node successorParent = delNode;
// 删除节点的替补节点
Node successor = delNode;
Node current = delNode.rightChild;
while (current != null) {
// successorParent指向当前节点的上一个节点
successorParent = successor;
// successor变为当前节点
successor = current;
current = current.leftChild;
}
// 替补节点的右孩子节点不为空
if (successor != delNode.rightChild) {
successorParent.leftChild = successor.rightChild;
successor.rightChild = delNode.rightChild;
}
return successor;
}
}
public class TreeApp {
public static void main(String[] args) {
Tree tree = new Tree();
tree.insert(8);
tree.insert(50);
tree.insert(45);
tree.insert(21);
tree.insert(32);
tree.insert(18);
tree.insert(37);
tree.insert(64);
tree.insert(88);
tree.insert(5);
tree.insert(4);
tree.insert(7);
System.out.print("PreOrder : ");
tree.traverse(1);
System.out.println();
System.out.print("InOrder : ");
tree.traverse(2);
System.out.println();
System.out.print("PostOrder : ");
tree.traverse(3);
System.out.println();
System.out.println(tree.delete(7));
System.out.print("PreOrder : ");
tree.traverse(1);
System.out.println();
System.out.print("InOrder : ");
tree.traverse(2);
System.out.println();
System.out.print("PostOrder : ");
tree.traverse(3);
System.out.println();
}
}
这个是java中的forEach循环，和
for(int i =0 ;i 10 ;i++){...}
还是有点区别的。有问题可以继续 问。
树节点类：
package cn点抗 .tree;
public class Node {
private Integer id;
private Integer parentId;
private String name;
private String link;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Integer getParentId() {
return parentId;
}
public void setParentId(Integer parentId) {
this.parentId = parentId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getLink() {
return link;
}
public void setLink(String link) {
this.link = link;
}
}
输出树形菜单类：
package cn点抗 .tree;
import java.util.ArrayList;
import java.util.List;
public class Tree {
private StringBuffer html = new StringBuffer();
private ListNode nodes;
public Tree(ListNode nodes){
this.nodes = nodes;
}
public String buildTree(){
html.append("ul");
for (Node node : nodes) {
Integer id = node.getId();
if (node.getParentId() == null) {
html.append("\r\nli id='" + id + "'" + node.getName()+ "/li");
build(node);
}
}
html.append("\r\n/ul");
return html.toString();
}
private void build(Node node){
ListNode children = getChildren(node);
if (!children.isEmpty()) {
html.append("\r\nul");
for (Node child : children) {
Integer id = child.getId();
html.append("\r\nli id='" + id + "'" + child.getName()+ "/li");
build(child);
}
html.append("\r\n/ul");
}
}
private ListNode getChildren(Node node){
ListNode children = new ArrayListNode();
Integer id = node.getId();
for (Node child : nodes) {
if (id.equals(child.getParentId())) {
children.add(child);
}
}
return children;
}
}
测试类：
package zzj.test;
import java.util.ArrayList;
import java.util.List;
import cn点抗 .tree.Node;
import cn点抗 .tree.Tree;
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
ListNode nodes = new ArrayListNode();
Node node1 = new Node();
node1.setId(1);
node1.setName("node1");
node1.setParentId(null);
node1.setLink(null);
nodes.add(node1);
Node node11 = new Node();
node11.setId(11);
node11.setName("node11");
node11.setParentId(1);
node11.setLink(null);
nodes.add(node11);
Node node111 = new Node();
node111.setId(111);
node111.setName("node111");
node111.setParentId(11);
node111.setLink(null);
nodes.add(node111);
Node node12 = new Node();
node12.setId(12);
node12.setName("node12");
node12.setParentId(1);
node12.setLink(null);
nodes.add(node12);
Node node2 = new Node();
node2.setId(2);
node2.setName("node2");
node2.setParentId(null);
node2.setLink(null);
nodes.add(node2);
Node node21 = new Node();
node21.setId(21);
node21.setName("node21");
node21.setParentId(2);
node21.setLink(null);
nodes.add(node21);
Node node3 = new Node();
node3.setId(3);
node3.setName("node3");
node3.setParentId(null);
node3.setLink(null);
nodes.add(node3);
Tree tree = new Tree(nodes);
System.out.println(tree.buildTree());
}
}