LeetCode 430 Flatten a Multilevel Doubly Linked List Solution Explained скачать в хорошем качестве

LeetCode 430 Flatten a Multilevel Doubly Linked List Solution Explained

In this video, we solve LeetCode Problem 430: Flatten a Multilevel Doubly Linked List, a classic data structures problem that combines linked lists and depth-first traversal. This problem is very important for coding interviews because it tests your understanding of pointer manipulation, recursion, and list flattening. 🧠 Problem Logic You are given a doubly linked list where each node contains: a previous pointer a next pointer a child pointer (which may point to another doubly linked list) The goal is to flatten this multilevel structure into a single-level doubly linked list. Rules to follow: If a node has a child list, the child list must appear right after the current node The original next node should appear after the child list All child pointers must be set to null in the final list ✔️ Approach Used (Depth First Search) We traverse the list node by node. When a node has a child: Recursively flatten the child list Attach the child list between the current node and the next node Fix previous and next pointers carefully Set the child pointer to null This ensures the list is flattened in the correct order. 🔗 Problem Link https://leetcode.com/problems/flatten-a-mu... 📊 Complexity Analysis Time Complexity: O(n), where n is the total number of nodes Space Complexity: O(n) due to recursion stack 👨‍💻 Code Logic (Pseudocode) function flattenList(node): current = node last = null while current exists: nextNode = current.next if current has child: childHead = flattenList(current.child) current.next = childHead childHead.prev = current current.child = null find tail of child list tail.next = nextNode if nextNode exists: nextNode.prev = tail last = tail else: last = current current = nextNode return node 👋 About Me Hi, I’m Ajmain Fayek Diganta, a CSE student at BUET. I upload videos on LeetCode, Competitive Programming, Algorithms, Data Structures, and C plus plus problem solving to help students prepare for interviews and contests. 🔗 GitHub: https://github.com/DIGANTA100 🔗 LinkedIn: https://www.linkedin.com/in/ajmain-fayek-d... Subscribe for more clean explanations and interview-focused solutions. 🔖 Hashtags #LeetCode #LeetCode430 #LinkedList #FlattenLinkedList #DataStructures #DFS #CodingInterview #ProblemSolving #AjmainFayekDiganta #BUET #CSE #CPlusPlus #Python