二叉树增加中序后续，层级遍历

php/24_tree/Tree.php

@@ -149,4 +149,58 @@ class Tree
         $this->preOrder($node->left);
         $this->preOrder($node->right);
     }
+
+    /**中序遍历
+     * @param $node
+     *
+     */
+    public function inOrder($node){
+        if(empty($node)){
+            return;
+        }
+        $this->inOrder($node->left);
+        echo $node->data . ' ';
+        $this->inOrder($node->right);
+
+    }
+
+    /**
+     * @param $node
+     * 后续遍历
+     */
+    public function postOrder($node){
+        if(empty($node)){
+            return;
+        }
+        $this->postOrder($node->left);
+        $this->postOrder($node->right);
+        echo $node->data . ' ';
+
+    }
+    /**
+     * @param $queue
+     * @param int $index 从队列(数组)的那个位置开始处理
+     * 层级遍历
+     * 首先把节点放入数组，记录放入数组的根节点个数index，把节点的左右子放入数组
+     * 开始遍历数组queue(从index开始,子节点已经入队列的节点元素不再处理)，把左右子节点放入queue,index++
+     * 持续上述过程，当节点没有子节点时，入队列过程结束，queue里节点的顺序即为层级遍历元素节点的顺序
+     */
+    public function levelOrder(&$queue,$index=0){
+        $len=count($queue);
+        for($i=$index;$i<$len;$i++){
+            $node=$queue[$i];
+            if($node->left){
+                $queue[]=$node->left;
+            }else{
+                return;
+            }
+            if($node->right){
+                $queue[]=$node->right;
+            }else{
+                return ;
+            }
+            $index++;
+        }
+        $this->levelOrder($queue,$index);
+    }
 }

php/24_tree/levelOrder.php

@@ -0,0 +1,34 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: 764432054@qq.com
+ * Date: 2019/9/22
+ * Time: 23:30
+ *
+ *二叉树的层级遍历
+ */
+
+
+namespace Algo_24;
+
+require_once '../vendor/autoload.php';
+
+$tree=new Tree(20);
+$tree->insert(16);
+$tree->insert(30);
+$tree->insert(12);
+$tree->insert(19);
+
+$tree->insert(10);
+$tree->insert(15);
+$tree->insert(18);
+$tree->insert(21);
+$tree->insert(38);
+
+$q=[$tree->head];
+$tree->levelOrder($q);
+
+foreach ($q as $n){
+    echo $n->data." ";
+}
+echo PHP_EOL;

php/24_tree/main.php

@@ -9,6 +9,7 @@ $tree = new Tree();
 
 $tree->insert(20);
 $tree->insert(30);
+$tree->insert(40);
 $tree->insert(10);
 $tree->insert(21);
 $tree->insert(22);
@@ -16,7 +17,14 @@ $tree->insert(22);
 $tree->preOrder($tree->head);
 echo PHP_EOL;
 
-var_dump($tree->find(30));
+$tree->inOrder($tree->head);
+echo PHP_EOL;
+
+$tree->postOrder($tree->head);
+echo PHP_EOL;
+
+
+print_r($tree->find(30));
 echo PHP_EOL;