二叉树
一、二叉树是什么？
二、源码
1.Heronode类
代码如下（示例）：
package BinaryTree;
public class Heronode {
private int no;
private String name;
private Heronode left;
private Heronode right;
public Heronode(int no, String name) {
this.no = no;
this.name = name;
}
public int getNo() {
return no;
}
public void setNo(int no) {
this.no = no;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Heronode getLeft() {
return left;
}
public void setLeft(Heronode left) {
this.left = left;
}
public Heronode getRight() {
return right;
}
public void setRight(Heronode right) {
this.right = right;
}
@Override
public String toString() {
return "Heronode{" +
"no=" + no +
", name='" + name + '\'' +
'}';
}
//前序遍历 利用递归的方法
public void preOrder() {
System.out.println(this); //先输出父节点
//向左递归
if (this.left != null) {
this.left.preOrder();
}
//向右递归
if (this.right != null) {
this.right.preOrder();
}
}
//中序遍历
public void infixOrder() {
if (this.left != null) {
this.left.infixOrder();
}
System.out.println(this);
if (this.right != null) {
this.right.infixOrder();
}
}
//后续遍历
public void postOrder() {
if (this.left != null) {
this.left.postOrder();
}
if (this.right != null) {
this.right.postOrder();
}
System.out.println(this);
}
//前序查找
public Heronode proOrderSearch(int no) {
Heronode resultnode = null;
if (this.no == no) {
return this;
}
if (this.left != null) {
resultnode = this.left.proOrderSearch(no);
}
if (resultnode != null) {
return resultnode;
}
if (this.right != null) {
resultnode = this.right.proOrderSearch(no);
}
return resultnode;
}
//中序查找
public Heronode infixOrderSearch(int no) {
Heronode resultnode = null;
if (this.left != null) {
resultnode = this.left.infixOrderSearch(no);
}
if (resultnode != null) {
return resultnode;
}
if (this.no == no) {
return this;
}
if (this.right != null) {
resultnode = this.right.infixOrderSearch(no);
}
return resultnode;
}
//后序查找
public Heronode postOrderSearch(int no) {
Heronode resultnode = null;
if (this.left != null) {
resultnode = this.left.postOrderSearch(no);
}
if (resultnode != null) {
return resultnode;
}
if (this.right != null) {
resultnode = this.right.postOrderSearch(no);
}
if (resultnode != null) {
return resultnode;
}
if (this.no == no) {
return this;
}
return resultnode;
}
//删除某个节点
public void deletenode(int no) {
if (this.left != null && this.left.no == no) {
this.left = null;
return;
}
if (this.right != null && this.right.no == no) {
this.right = null;
return;
}
if (this.left != null) {
this.left.deletenode(no);
}
if (this.right != null) {
this.right.deletenode(no);
}
}
}
2.BinaryTree类
代码如下（示例）：
package BinaryTree;
public class BinaryTree {
private Heronode root;
public void setRoot(Heronode root) {
this.root = root;
}
//前序遍历
public void preOrder() {
if (this.root != null) {
this.root.preOrder();
} else {
System.out.println("二叉树为空，无法遍历");
}
}
//中序遍历
public void infixOrder() {
if (this.root != null) {
this.root.infixOrder();
} else {
System.out.println("二叉树为空，无法遍历");
}
}
//后续遍历
public void postOrder() {
if (this.root != null) {
this.root.postOrder();
} else {
System.out.println("二叉树为空，无法遍历");
}
}
//前序查找
public Heronode proOrderSearch(int no) {
if (this.root != null) {
return this.root.proOrderSearch(no);
} else {
return null;
}
}
//中序查找
public Heronode infixOrderSearch(int no) {
if (this.root != null) {
return this.root.infixOrderSearch(no);
} else {
return null;
}
}
//后序查找
public Heronode postOrderSearch(int no) {
if (this.root != null) {
return this.root.postOrderSearch(no);
} else {
return null;
}
}
//删除节点
public void deletenode(int no) {
if (this.root != null) {
if (this.root.getNo() == no) {
this.root = null;
} else {
this.root.deletenode(no);
}
} else {
System.out.println("二叉树为空，无法删除节点");
}
}
}
3.BinaryTreeDemo
代码如下（示例）：
package BinaryTree;
public class BinaryTreeDemo {
public static void main(String[] args) {
Heronode heronode1 = new Heronode(1,"james");
Heronode heronode2 = new Heronode(2,"davis");
Heronode heronode3 = new Heronode(3,"polo");
Heronode heronode4 = new Heronode(4,"towns");
Heronode heronode5 = new Heronode(5,"rose");
BinaryTree binaryTree = new BinaryTree();
binaryTree.setRoot(heronode1);
heronode1.setLeft(heronode2);
heronode1.setRight(heronode3);
heronode3.setLeft(heronode5);
heronode3.setRight(heronode4);
System.out.println("前序遍历");
binaryTree.preOrder();
System.out.println("=============");
Heronode resultheronode = binaryTree.proOrderSearch(5);
if (resultheronode!=null){
System.out.printf("找到编号为%d,姓名为%s\n",resultheronode.getNo(),resultheronode.getName());
}else {
System.out.printf("没有找到编号为%d",5);
}
System.out.println("=============");
binaryTree.deletenode(5);
System.out.println("删除后，前序遍历");
binaryTree.preOrder();
}
}
总结
理清楚思路，debug下就懂了