Added binary tree example in PHP

Author: Alienpruts

chap-06/binary-tree-example.php

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+<?php
+/**
+ * Created by PhpStorm.
+ * User: bert
+ * Date: 6/10/18
+ * Time: 15:13
+ */
+
+use App\Chapter06\BinaryNode;
+use App\Chapter06\BinaryTree;
+
+require_once __DIR__ . "/../vendor/autoload.php";
+
+$final = new BinaryNode("Final");
+
+$tree = new BinaryTree($final);
+
+$semiFinal1 = new BinaryNode("Semi Final 1");
+$semiFinal2 = new BinaryNode("Semi Final 2");
+$quarterFinal1 = new BinaryNode("Quarter Final 1");
+$quarterFinal2 = new BinaryNode("Quarter Final 2");
+$quarterFinal3 = new BinaryNode("Quarter Final 3");
+$quarterFinal4 = new BinaryNode("Quarter Final 4");
+
+$semiFinal1->addChildren($quarterFinal1,$quarterFinal2);
+$semiFinal2->addChildren($quarterFinal3,$quarterFinal4);
+
+$final->addChildren($semiFinal1, $semiFinal2);
+
+$tree->traverse($tree->root);

src/Chapter06/BinaryNode.php

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+<?php
+/**
+ * Created by PhpStorm.
+ * User: bert
+ * Date: 6/10/18
+ * Time: 13:52
+ */
+
+namespace App\Chapter06;
+
+
+class BinaryNode
+{
+    public $data;
+    public $left;
+    public $right;
+
+    /**
+     * BinaryNode constructor.
+     * @param $data
+     */
+    public function __construct( string $data = NULL)
+    {
+        $this->data = $data;
+        $this->left = NULL;
+        $this->right = NULL;
+    }
+
+    public function addChildren(BinaryNode $right, BinaryNode $left)
+    {
+        $this->left = $left;
+        $this->right = $right;
+    }
+
+
+}

src/Chapter06/BinaryTree.php

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+<?php
+/**
+ * Created by PhpStorm.
+ * User: bert
+ * Date: 6/10/18
+ * Time: 14:02
+ */
+
+namespace App\Chapter06;
+
+
+class BinaryTree
+{
+    public $root = NULL;
+
+    /**
+     * BinaryTree constructor.
+     * @param null $root
+     */
+    public function __construct(BinaryNode $node)
+    {
+        $this->root = $node;
+    }
+
+    /**
+     * Traverse Binary Tree recursively.
+     * @param BinaryNode $node
+     * @param int $level
+     */
+    public function traverse(BinaryNode $node, int $level = 0)
+    {
+        if ($node){
+            echo str_repeat("-" ,$level);
+            echo $node->data . PHP_EOL;
+
+            if ($node->right) {
+                $this->traverse($node->right, $level + 1);
+            }
+            if ($node->left) {
+                $this->traverse($node->left, $level + 1);
+            }
+        }
+    }
+
+
+}