From f7a21e419cace3de43e9f0d0dd564cf1a06cc623 Mon Sep 17 00:00:00 2001
From: Kai Jiang <jiangkai@gmail.com>
Date: Mon, 27 Nov 2017 11:21:18 -0800
Subject: [PATCH] Update convert-binary-search-tree-to-doubly-linked-list.cpp

---
 ...nary-search-tree-to-doubly-linked-list.cpp | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/C++/convert-binary-search-tree-to-doubly-linked-list.cpp b/C++/convert-binary-search-tree-to-doubly-linked-list.cpp
index 3ace3db..d379c3e 100644
--- a/C++/convert-binary-search-tree-to-doubly-linked-list.cpp
+++ b/C++/convert-binary-search-tree-to-doubly-linked-list.cpp
@@ -51,3 +51,37 @@ class Solution {
       treeToDoublyList(p->right, prev, head);
     }
 };
+
+
+
+
+// A simple recursive function to convert a given Binary tree to Doubly
+// Linked List
+// root --> Root of Binary Tree
+// head --> Pointer to head node of created doubly linked list
+void BinaryTree2DoubleLinkedList(node *root, node **head)
+{
+    // Base case
+    if (root == NULL) return;
+ 
+    // Initialize previously visited node as NULL. This is
+    // static so that the same value is accessible in all recursive
+    // calls
+    static node* prev = NULL;
+ 
+    // Recursively convert left subtree
+    BinaryTree2DoubleLinkedList(root->left, head);
+ 
+    // Now convert this node
+    if (prev == NULL)
+        *head = root;
+    else
+    {
+        root->left = prev;
+        prev->right = root;
+    }
+    prev = root;
+ 
+    // Finally convert right subtree
+    BinaryTree2DoubleLinkedList(root->right, head);
+}