数据结构 – 线索化二叉树(Java)
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博客阐明
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阐明
- n 个结点的二叉链表中含有 n +1【公式 2n-(n-1)=n+1】个空指针域。利用二叉链表中的空指针域,寄存指向该结点在某种遍历秩序下的前驱和后继结点的指针(这种附加的指针称为 ” 线索 ”)
- 这种加上了线索的二叉链表称为线索链表,相应的二叉树称为线索二叉树 (Threaded BinaryTree)。依据线索性质的不同,线索二叉树可分为前序线索二叉树、中序线索二叉树和后序线索二叉树三种
- 一个结点的前一个结点,称为前驱结点
- 一个结点的后一个结点,称为后继结点
代码
package cn.guizimo.thread.tree;
/**
* @author guizimo
* @date 2020/8/7 11:08 上午
*/
public class ThreadTree {public static void main(String[] args) {
// 设置节点
HeroNode root = new HeroNode(1, "tom");
HeroNode node2 = new HeroNode(3, "jack");
HeroNode node3 = new HeroNode(6, "smith");
HeroNode node4 = new HeroNode(8, "mary");
HeroNode node5 = new HeroNode(10, "king");
HeroNode node6 = new HeroNode(14, "dim");
// 设置二叉树
root.setLeft(node2);
root.setRight(node3);
node2.setLeft(node4);
node2.setRight(node5);
node3.setLeft(node6);
// 线索化
ThreadedBinaryTree threadedBinaryTree = new ThreadedBinaryTree();
threadedBinaryTree.setRoot(root);
threadedBinaryTree.threadedNodes();
// 遍历
threadedBinaryTree.threadedList();}
}
/**
* 二叉树
*/
class ThreadedBinaryTree {
// 根节点
private HeroNode root;
// 辅助节点
private HeroNode pre = null;
public void setRoot(HeroNode root) {this.root = root;}
public void threadedNodes() {this.threadedNodes(root);
}
// 中序遍历
public void threadedList() {
HeroNode node = root;
while (node != null) {while (node.getLeftType() == 0) {node = node.getLeft();
}
System.out.println(node);
while (node.getRightType() == 1) {node = node.getRight();
System.out.println(node);
}
node = node.getRight();}
}
// 线索化
public void threadedNodes(HeroNode node) {if(node == null) {return;}
threadedNodes(node.getLeft());
if(node.getLeft() == null) {node.setLeft(pre);
node.setLeftType(1);
}
if (pre != null && pre.getRight() == null) {pre.setRight(node);
pre.setRightType(1);
}
pre = node;
threadedNodes(node.getRight());
}
// 删除二叉树的节点
public void delNode(int no) {if (root != null) {if (root.getNo() == no) {root = null;} else {root.delNode(no);
}
} else {System.out.println("二叉树为空");
}
}
// 前序
public void preOrder() {if (this.root != null) {this.root.preOrder();
} else {System.out.println("二叉树为空");
}
}
// 中序
public void infixOrder() {if (this.root != null) {this.root.infixOrder();
} else {System.out.println("二叉树为空");
}
}
// 后序
public void postOrder() {if (this.root != null) {this.root.postOrder();
} else {System.out.println("二叉树为空");
}
}
// 前序查找
public HeroNode preOrderSearch(int no) {if (root != null) {return root.preOrderSearch(no);
} else {return null;}
}
// 中序查找
public HeroNode infixOrderSearch(int no) {if (root != null) {return root.infixOrderSearch(no);
} else {return null;}
}
// 后序查找
public HeroNode postOrderSearch(int no) {if (root != null) {return this.root.postOrderSearch(no);
} else {return null;}
}
}
/**
* 节点
*/
class HeroNode {
private int no;
private String name;
private HeroNode left;
private HeroNode right;
public int getLeftType() {return leftType;}
public void setLeftType(int leftType) {this.leftType = leftType;}
public int getRightType() {return rightType;}
public void setRightType(int rightType) {this.rightType = rightType;}
private int leftType;
private int rightType;
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 + '\'' +
'}';
}
// 删除节点
public void delNode(int no) {
// 判读左节点是否为空,找到
if (this.left != null && this.left.no == no) {
this.left = null;
return;
}
// 判断右节点,找到
if (this.right != null && this.right.no == no) {
this.right = null;
return;
}
// 判断左节点,未找到,递归
if (this.left != null) {this.left.delNode(no);
}
// 判断右节点,未找到,递归
if (this.right != null) {this.right.delNode(no);
}
}
// 前序
public void preOrder() {System.out.println(this);
if (this.left != null) {this.left.preOrder();
}
if (this.right != null) {this.right.preOrder();
}
}
// 中序
public void infixOrder() {if (this.left != null) {this.left.infixOrder();
}
System.out.println(this);
if (this.right != null) {this.right.infixOrder();
}
}
// 后序
public void postOrder() {if (this.left != null) {this.left.postOrder();
}
if (this.right != null) {this.right.postOrder();
}
System.out.println(this);
}
// 前序遍历查找
public HeroNode preOrderSearch(int no) {if (this.no == no) {return this;}
HeroNode resNode = null;
// 判断左子树
if (this.left != null) {resNode = this.left.preOrderSearch(no);
}
if (resNode != null) {return resNode;}
// 判断右子树
if (this.right != null) {resNode = this.right.preOrderSearch(no);
}
return resNode;
}
// 中序遍历查找
public HeroNode infixOrderSearch(int no) {
HeroNode resNode = null;
if (this.left != null) {resNode = this.left.infixOrderSearch(no);
}
if (resNode != null) {return resNode;}
if (this.no == no) {return this;}
if (this.right != null) {resNode = this.right.infixOrderSearch(no);
}
return resNode;
}
// 后序遍历查找
public HeroNode postOrderSearch(int no) {
HeroNode resNode = null;
if (this.left != null) {resNode = this.left.postOrderSearch(no);
}
if (resNode != null) {return resNode;}
if (this.right != null) {resNode = this.right.postOrderSearch(no);
}
if (resNode != null) {return resNode;}
if (this.no == no) {return this;}
return resNode;
}
}
感激
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