Reverse Nodes in k-Group | LeetCode 25 | Google Interview Question

Ready to master one of the toughest linked list problems? In this video, we'll solve LeetCode problem 25. Reverse Nodes in k-Group. The challenge is to reverse the nodes of a linked list in groups of k, leaving the last group as is if its size is less than k. My solution uses a robust block-reversal strategy that's easy to follow. Here's the logic we'll cover: Block-by-Block Traversal: The main idea is to iterate through the linked list and process it in chunks of k nodes. Counting and Reversal: We use a counter to keep track of the number of nodes we have traversed. When the counter reaches k, we know we've found a full group that needs to be reversed. The reverse Function: We'll use a separate helper function to reverse a single linked list block. This function takes the head of a block and returns the new head of that reversed block. Connecting the Blocks: The most crucial part is correctly connecting the reversed blocks. The end of the previous reversed block must point to the head of the current reversed block. We use a lastEnd pointer to keep track of the tail of the last reversed group and update its next pointer. Handling the Tail: If the last remaining nodes form a group smaller than k, they are left as is, which our logic naturally handles by not reversing them. This solution is a clean way to handle the problem by breaking it down into manageable subproblems: reversing a single block and then connecting these blocks together. This approach is highly useful for similar linked list manipulation problems. #LeetCode #LinkedList #ReverseNodes #KGroupReversal #ProblemSolving #CodingInterview #DataStructuresAndAlgorithms #LeetCode25 #Cplusplus #Programming #TechInterview #DSA