diff --git a/leetcode/104.php b/leetcode/104.php
index 0f87008..a7bcc36 100644
--- a/leetcode/104.php
+++ b/leetcode/104.php
@@ -36,6 +36,15 @@ function one($root)
     {
         return $root === null ? 0 : max( $this->one( $root->left ), $this->one( $root->right ) ) + 1;
     }
+
+    function two($root){
+        if (!$root){
+            return 0;
+        }
+        $left  = $this->maxDepth( $root->left );
+        $right = $this->maxDepth( $root->right );
+        return max($left,$right)+1;
+    }
 }
 
 $a        = new TreeNode( 3 );
diff --git a/leetcode/50.php b/leetcode/50.php
new file mode 100644
index 0000000..63d84ef
--- /dev/null
+++ b/leetcode/50.php
@@ -0,0 +1,39 @@
+<?php
+
+class Solution
+{
+
+    /**
+     * @param Float   $x
+     * @param Integer $n
+     *
+     * @return Float
+     */
+    function myPow($x, $n)
+    {
+        if ($n == 0) {
+            return 1;
+        }
+        if ($n < 0) {
+            $x = 1 / $x;
+            $n = abs( $n );
+        }
+        $size = $this->size( $x, $n );
+        return $size;
+    }
+
+    function size($x, $n)
+    {
+        if ($n == 1) {
+            return $x;
+        }
+        $size = $this->size( $x, floor( $n / 2 ) );
+        return $n % 2 ? $size * $size * $x : $size * $size;
+    }
+}
+
+$x        = 2;
+$n        = 3;
+$solution = new Solution();
+$b        = $solution->myPow( $x, $n );
+var_dump( $b );
\ No newline at end of file