206. Reverse Linked List

reverse-linked-list.go

// https://leetcode.com/problems/reverse-linked-list/
//
// Time:  O(N)
// Space: O(1)
//
// N = number of nodes in the list

// .................... //

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

    for curr != nil {
        next := curr.Next
        curr.Next = prev
        prev = curr
        curr = next
    }

    return prev
}