Create flatten_list.py

linked_lists/flatten_list.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# author: bt3gl
+
+
+
+class Node:
+    def __init__(self, val, prev, next, child):
+        self.val = val
+        self.prev = prev
+        self.next = next
+        self.child = child
+
+
+def dfs(prev, node):
+  
+        if not node:
+            return prev
+
+        node.prev = prev
+        prev.next = node
+        temp_next = node.next
+  
+        last = dfs(node, node.child)
+        node.child = None
+  
+        return dfs(last, temp_next)
+
+
+    def flatten(head):
+        
+        if head is None:
+            return head
+
+        pseudo_head = Node(None, None, head, None)
+      
+        dfs(pseudo_head, head)
+        pseudo_head.next.prev = None
+      
+        return pseudo_head.next