Add solution 145.

Author: javadev

src/Algorithms/0145.binary-tree-postorder-traversal/binary-tree-postorder-traversal.php

@@ -0,0 +1,30 @@
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     public $val = null;
+ *     public $left = null;
+ *     public $right = null;
+ *     function __construct($value) { $this->val = $value; }
+ * }
+ */
+class Solution {
+
+    /**
+     * @param TreeNode $root
+     * @return Integer[]
+     */
+    function postorderTraversal($root) {
+        $postOrder = [];
+        $stack = [];
+        $node = $root;
+        while (!empty($stack) || $node != null) {
+            while ($node != null) {
+                array_push($stack, $node);
+                array_unshift($postOrder, $node->val);
+                $node = $node->right;
+            }
+            $node = array_pop($stack)->left;
+        }
+        return $postOrder;
+    }
+}