完善24二叉树基本算法

php/24_tree/Tree.php

@@ -0,0 +1,152 @@
+<?php
+
+namespace Algo_24;
+
+class Tree
+{
+
+    /**
+     * 树的根节点
+     * @var [type]
+     */
+    public $head = null;
+
+    /**
+     * [__construct description]
+     * @param TreeNode|null $head [description]
+     */
+    public function __construct($headData = null)
+    {
+        if ($headData != null) {
+            $this->head = new TreeNode($headData);
+        }
+    }
+
+    /**
+     * 查找数据
+     * @param  [type] $data [数据]
+     * @return [type]       [description]
+     */
+    public function find($data)
+    {
+        if ($this->head == null) {
+            return null;
+        }
+
+        $node = $this->head;
+
+        while ($node != null) {
+            if ($node->data == $data) {
+                return $node;
+            } elseif ($data > $node->data) {
+                $node = $node->right;
+            } else {
+                $node = $node->left;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * 插入数据
+     * @param  [type] $data [数据]
+     * @return [type]       [description]
+     */
+    public function insert($data)
+    {
+        if ($this->head == null) {
+            $this->head = new TreeNode($data);
+            return true;
+        }
+
+        $node = $this->head;
+
+        while ($node != null) {
+            if ($data > $node->data) {
+                if ($node->right == null) {
+                    $node->right = new TreeNode($data);
+                    return true;
+                }
+                $node = $node->right;
+            } else {
+                if ($node->left == null) {
+                    $node->left = new TreeNode($data);
+                    return true;
+                }
+                $node = $node->left;
+            }
+        }
+    }
+
+    /**
+     * 删除节点
+     * @param  [type] $data [节点]
+     * @return [type]       [description]
+     */
+    public function delete($data)
+    {
+        // 找到需要删除节点
+        $node = $this->head;
+        $pnode = null;
+        while ($node != null) {
+            if ($node->data == $data) {
+                break;
+            } elseif ($data > $node->data) {
+                $pnode = $node;
+                $node = $node->right;
+            } else {
+                $pnode = $node;
+                $node = $node->left;
+            }
+        }        
+        if ($node == null) {
+            return false;
+        }
+        // 要删除的节点有两个子节点
+        // 查找右子树中最小节点
+        if ($node->left != null && $node->right != null) {
+            $minPP = $node;
+            $minP = $node->right;
+            while ($minP->left != null) {
+                $minPP = $minP;
+                $minP = $minP->left;
+            }
+            $node->data = $minP->data;
+            $node = $minP;
+            // 删除掉右子树中的最小节点
+            $minPP->left = null;
+        }
+
+        if ($node->left != null) {
+            $child = $node->left;
+        } elseif ($node->right != null) {
+            $child = $node->right;
+        } else {
+            $child = null;
+        }
+
+        if ($pnode == null) {
+            // 删除的是根节点
+            $node = $child;
+        } elseif ($pnode->left == $node) {
+            $pnode->left = $child;
+        } else {
+            $pnode->right = $child;
+        }
+    }
+
+    /**
+     * 前序遍历
+     * @return [type] [description]
+     */
+    public function preOrder($node)
+    {
+        if ($node == null) {
+            return ;            
+        }
+        echo $node->data . '->';
+        $this->preOrder($node->left);
+        $this->preOrder($node->right);
+    }
+}

php/24_tree/TreeNode.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace Algo_24;
+
+class TreeNode
+{
+
+    /**
+     * 节点中的数据
+     * @var [type]
+     */
+    public $data;
+
+    /**
+     * 左节点
+     * @var [type]
+     */
+    public $left;
+
+    /**
+     * 右节点
+     * @var [type]
+     */
+    public $right;
+
+    /**
+     * [__construct description]
+     * @param [type] $data [description]
+     */
+    public function __construct($data = null)
+    {
+        $this->data = $data;
+        $this->left = null;
+        $this->right = null;
+    }
+}

php/24_tree/main.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace Algo_24;
+
+require_once '../vendor/autoload.php';
+
+
+$tree = new Tree();
+
+$tree->insert(20);
+$tree->insert(30);
+$tree->insert(10);
+$tree->insert(21);
+$tree->insert(22);
+
+$tree->preOrder($tree->head);
+echo PHP_EOL;
+
+var_dump($tree->find(30));
+echo PHP_EOL;
+
+
+$tree->delete(30);
+$tree->preOrder($tree->head);
+echo PHP_EOL;

php/composer.json

@@ -8,7 +8,8 @@
             "Algo_06\\": "06_linkedlist/",
             "Algo_07\\": "07_linkedlist/",
             "Algo_08\\": "08_stack/",
-            "Algo_09\\": "09_queue/"
+            "Algo_09\\": "09_queue/",
+            "Algo_24\\": "24_tree/"
         }
     }
 }