430. Flatten a Multilevel Doubly Linked List

Author: shubhamvishu

Data Structures/Linked List/FlattenMultilevelDoublyLinkedList.cpp

@@ -0,0 +1,34 @@
+//https://leetcode.com/problems/flatten-a-multilevel-doubly-linked-list/
+
+class Solution {
+public:
+    Node* flatten(Node* head) {
+        flattenList(head);
+        return head;
+    }
+    Node* flattenList(Node* head){
+        if(head==NULL) return NULL;
+        Node* temp = head;
+        Node* curr = temp;
+
+        if(temp->child!=NULL){
+            Node* remain = temp->next;
+            temp->next = temp->child;
+            temp->child->prev = temp;
+            temp->child = NULL;
+            curr = flattenList(temp->next);
+            if(remain!=NULL){
+                curr->next = remain;
+                remain->prev = curr;
+                return flattenList(remain);
+            }
+            return curr;
+        }
+        else if(temp->next!=NULL){
+            return flattenList(temp->next);
+        }
+        else {
+            return temp;
+        }
+    }
+};