How to reverse linked list in golang

Linked list reversal is a common algorithm problem, which requires reversing the order of the linked list. For the Golang language, the implementation of linked list inversion can be implemented using basic language features such as Golang pointers and structures.

Below we will introduce the Golang implementation of linked list inversion in detail.

First, let’s take a look at the basic structure of a linked list. A linked list is composed of nodes, and each node has a pointer to the next node, that is, the next pointer. The head node of the linked list represents the starting position of the entire linked list, and the next pointer of the head node points to the first node. As shown below:

type ListNode struct {
    Val  int
    Next *ListNode
}

Among them, Val represents the value of the node, and Next represents the pointer to the next node. Two issues need to be paid attention to in the implementation of linked list:

1. Need to record the pointer of the head node of the linked list
2. Need to record the pointer of the current node and the next node

After completing the definition of the linked list, you can write the Golang implementation of linked list inversion. The specific implementation method is as follows:

func reverseList(head *ListNode) *ListNode {
    //边界条件
    if head == nil || head.Next == nil {
        return head
    }
    //定义当前节点和下一个节点指针
    cur, next := head, head.Next
    //头节点指针置为空
    head.Next = nil
    for next != nil {
        //暂存下一个节点的指针
        tmp := next.Next
        //反转节点
        next.Next = cur
        //移动当前节点和下一个节点指针
        cur, next = next, tmp
    }
    return cur
}

First, judge the boundary conditions. If the linked list is empty or has only one node, directly return to the original linked list. Then define the current node pointer and next node pointer. Since linked list reversal requires the current node to point to the previous node, the previous node of the first node needs to be set to nil. Then reverse the linked list through a loop. The specific reversal operation is:

1. Temporarily store the pointer of the next node
2. Reverse the current node pointer to point to the previous node
3. Move the current node pointer and the next node pointer

Finally, return the reversed head node pointer of the linked list.

In the process of reversing the linked list using the above code, we need to call this function and pass in the linked list head pointer parameter. For example:

func main() {
    var head ListNode
    head.Next = &ListNode{Val: 1}
    head.Next.Next = &ListNode{Val: 2}
    head.Next.Next.Next = &ListNode{Val: 3}
    head.Next.Next.Next.Next = &ListNode{Val: 4}
    //链表反转
    head.Next = reverseList(head.Next)
    for head.Next != nil {
        fmt.Println(head.Next.Val)
        head.Next = head.Next.Next 
    }
}

In this sample code, we first construct a linked list with 5 nodes. Then call the reverse function to reverse it. Finally, by traversing the nodes, the reversed linked list nodes are output in order.

Through the above code examples, we can see that the Golang implementation of linked list inversion is relatively simple and common. By mastering the basic operations of linked lists and the use of pointers, we can easily implement the reversal operation of linked lists.

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