Detailed explanation of clue binary tree and binary tree traversal method implemented by PHP, detailed explanation of binary tree

This article describes the clue binary tree and binary tree traversal method implemented by PHP. Share it with everyone for your reference, the details are as follows:

<&#63;php
  require 'biTree.php';
  $str = 'ko#be8#tr####acy#####';
  $tree = new BiTree($str);
  $tree->createThreadTree();
  echo $tree->threadList() . "\n";從第一個結(jié)點開始遍歷線索二叉樹
  echo $tree->threadListReserv();從最后一個結(jié)點開始反向遍歷
&#63;>

biTree.php:

<&#63;
  /**
   * PHP實現(xiàn)二叉樹
   *
   * @author zhaojiangwei
   * @since 2011/10/25 10:32
   */
  //結(jié)點類
  class Node{
    private $data = NULL;
    private $left = NULL;
    private $right = NULL;
    private $lTag = 0;
    private $rTag = 0;
    public function Node($data = false){
      $this->data = $data;
    }
    //我不喜歡使用魔術(shù)方法
    public function getData(){
      return $this->data;
    }
    public function setData($data){
      $this->data = $data;
    }
    public function getLeft(){
      return $this->left;
    }
    public function setLeft($left){
      $this->left = $left;
    }
    public function getRight(){
      return $this->right;
    }
    public function setRight($right){
      $this->right = $right;
    }
    public function getLTag(){
      return $this->lTag;
    }
    public function setLTag($tag){
      $this->lTag = $tag;
    }
    public function getRTag(){
      return $this->rTag;
    }
    public function setRTag($tag){
      $this->rTag = $tag;
    }
  }
  //線索二叉樹類
  class BiTree{
    private $datas = NULL;//要導入的字符串;
    private $root = NULL; //根結(jié)點
    private $leafCount = 0;//葉子結(jié)點個數(shù)
    private $headNode = NULL; //線索二叉樹的頭結(jié)點
    private $preNode = NULL;//遍歷線索化二叉樹時保存前一個遍歷的結(jié)點
    public function BiTree($datas){
      is_array($datas) || $datas = str_split($datas);
      $this->datas = $datas;
      $this->backupData = $this->datas;
      $this->createTree(TRUE);
    }
    //前序遍歷創(chuàng)建樹
    //$root 判斷是不是要創(chuàng)建根結(jié)點
    public function createTree($root = FALSE){
      if(emptyempty($this->datas)) return NULL;
      $first = array_shift($this->datas);
      if($first == '#'){
        return NULL;
      }else{
        $node = new Node($first);
        $root && $this->root = $node;
        $node->setLeft($this->createTree());
        $node->setRight($this->createTree());
        return $node;
      }
    }
    //返回二叉樹葉子結(jié)點的個數(shù)
    public function getLeafCount(){
      $this->figureLeafCount($this->root);
      return $this->leafCount;
    }
    private function figureLeafCount($node){
      if($node == NULL)
        return false;
      if($this->checkEmpty($node)){
        $this->leafCount ++;
      }else{
        $this->figureLeafCount($node->getLeft());
        $this->figureLeafCount($node->getRight());
      }
    }
    //判斷結(jié)點是不是葉子結(jié)點
    private function checkEmpty($node){
      if($node->getLeft() == NULL && $node->getRight() == NULL){
        return true;
      }
      return false;
    }
    //返回二叉樹深度
    public function getDepth(){
      return $this->traversDepth($this->root);
    }
    //遍歷求二叉樹深度
    public function traversDepth($node){
      if($node == NULL){
        return 0;
      }
      $u = $this->traversDepth($node->getLeft()) + 1;
      $v = $this->traversDepth($node->getRight()) + 1;
      return $u > $v &#63; $u : $v;
    }
    //返回遍歷結(jié)果,以字符串的形式
    //$order 按遍歷形式返回,前中后
    public function getList($order = 'front'){
      if($this->root == NULL) return NULL;
      $nodeList = array();
      switch ($order){
        case "front":
          $this->frontList($this->root, $nodeList);
          break;
        case "middle":
          $this->middleList($this->root, $nodeList);
          break;
        case "last":
          $this->lastList($this->root, $nodeList);
          break;
        default:
          $this->frontList($this->root, $nodeList);
          break;
      }
      return implode($nodeList);
    }
    //創(chuàng)建線索二叉樹
    public function createThreadTree(){
      $this->headNode = new Node();
      $this->preNode = & $this->headNode;
      $this->headNode->setLTag(0);
      $this->headNode->setLeft($this->root);
      $this->headNode->setRTag(1);
      $this->threadTraverse($this->root);
      $this->preNode->setRight($this->headNode);
      $this->preNode->setRTag(1);
      $this->headNode->setRight($this->preNode);
    }
    //線索化二叉樹
    private function threadTraverse($node){
      if($node != NULL){
        if($node->getLeft() == NULL){
          $node->setLTag(1);
          $node->setLeft($this->preNode);
        }else{
          $this->threadTraverse($node->getLeft());
        }
        if($this->preNode != $this->headNode && $this->preNode->getRight() == NULL){
          $this->preNode->setRTag(1);
          $this->preNode->setRight($node);
        }
        $this->preNode = & $node;//注意傳引用
        $this->threadTraverse($node->getRight());
      }
    }
    //從第一個結(jié)點遍歷中序線索二叉樹
    public function threadList(){
      $arr = array();
      for($node = $this->getFirstThreadNode($this->root); $node != $this->headNode; $node = $this->getNextNode($node)){
        $arr[] = $node->getData();
      }
      return implode($arr);
    }
    //從尾結(jié)點反向遍歷中序線索二叉樹
    public function threadListReserv(){
      $arr = array();
      for($node = $this->headNode->getRight(); $node != $this->headNode; $node = $this->getPreNode($node)){
        $arr[] = $node->getData();
      }
      return implode($arr);
    }
    //返回某個結(jié)點的前驅(qū)
    public function getPreNode($node){
      if($node->getLTag() == 1){
        return $node->getLeft();
      }else{
        return $this->getLastThreadNode($node->getLeft());
      }
    }
    //返回某個結(jié)點的后繼
    public function getNextNode($node){
      if($node->getRTag() == 1){
        return $node->getRight();
      }else{
        return $this->getFirstThreadNode($node->getRight());
      }
    }
    //返回中序線索二叉樹的第一個結(jié)點
    public function getFirstThreadNode($node){
      while($node->getLTag() == 0){
        $node = $node->getLeft();
      }
      return $node;
    }
    //返回中序線索二叉樹的最后一個結(jié)點
    public function getLastThreadNode($node){
      while($node->getRTag() == 0){
        $node = $node->getRight();
      }
      return $node;
    }
    //前序遍歷
    private function frontList($node, & $nodeList){
      if($node !== NULL){
        $nodeList[] = $node->getData();
        $this->frontList($node->getLeft(), $nodeList);
        $this->frontList($node->getRight(), $nodeList);
      }
    }
    //中序遍歷
    private function middleList($node, & $nodeList){
      if($node != NULL){
        $this->middleList($node->getLeft(), $nodeList);
        $nodeList[] = $node->getData();
        $this->middleList($node->getRight(), $nodeList);
      }
    }
    //后序遍歷
    private function lastList($node, & $nodeList){
      if($node != NULL){
        $this->lastList($node->getLeft(), $nodeList);
        $this->lastList($node->getRight(), $nodeList);
        $nodeList[] = $node->getData();
      }
    }
    public function getData(){
      return $this->data;
    }
    public function getRoot(){
      return $this->root;
    }
  }
&#63;>

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