Week 50 @ 2024 算法周记【链表反转】

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func reverseList(head *ListNode) *ListNode {
    prev := (*ListNode)(nil)
    
    for head != nil {
        next := head.Next
        head.Next = prev
        prev = head
        head = next
    }
    
    return prev
}

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func reverseList(head *ListNode) *ListNode {
    if head == nil {
        return nil
    }
    if head.Next == nil {
        return head
    }
    
    next := head.Next
    newHead := reverseList(next)
    
    next.Next = head
    head.Next = nil
    
    return newHead
}