Program to reverse the Linked List (both iterative and recursive)
视频信息
答案文本
视频字幕
Welcome to our tutorial on linked list reversal. A linked list is a fundamental data structure where elements are stored in nodes, and each node points to the next one. Today we'll explore how to reverse a linked list using both iterative and recursive approaches. Here we see an original list with nodes containing values 1, 2, 3, 4, and after reversal, the order becomes 4, 3, 2, 1.
Now let's examine the iterative approach for reversing a linked list. The algorithm uses three pointers: prev, current, and next. We start with prev pointing to null and current pointing to the head of the list. In each iteration, we store the next node, reverse the current node's pointer to point to the previous node, then move all pointers forward. This process continues until we reach the end of the list.
Let's walk through the iterative reversal step by step. Initially, we have prev pointing to null and current pointing to the first node. In the first iteration, we store the next node, then reverse the current node's pointer to point to prev. After moving the pointers forward, we repeat this process. Each step gradually builds the reversed list by changing the direction of the pointers one by one.
The recursive approach uses a different strategy. It works by breaking down the problem into smaller subproblems. The base case handles empty lists or single nodes. For larger lists, we recursively reverse the tail, then adjust the connections. The key insight is that after reversing the tail, we need to reverse the connection between the current node and the next node, making the next node point back to the current node.
To summarize what we've learned about linked list reversal: We explored two fundamental approaches - the iterative method using three pointers and the recursive method that breaks the problem into smaller parts. Both achieve linear time complexity but differ in space usage. The iterative approach uses constant space while recursive uses stack space. These techniques form the foundation for solving many advanced linked list problems in computer science and software engineering.