Reversing a linked list

/*
This algorithm uses three pointers prev, curr, and nextTemp. 
The prev pointer is initially set to null, and the curr pointer is set to the head of the linked list. 
The algorithm then iterates through each node in the linked list, 
reversing the direction of each node’s pointer so that it points to the previous node instead of the next node.
The nextTemp pointer is used to temporarily store a reference to the next node in the linked list 
before it is overwritten by a new reference to the previous node.
The algorithm returns a reference to the new head of the reversed linked list, 
which is stored in the prev pointer.
*/


fun reverseList(head: ListNode?): ListNode? {
    var prev: ListNode? = null
    var curr = head
    while (curr != null) {
        val nextTemp = curr.next
        curr.next = prev
        prev = curr
        curr = nextTemp
    }
    return prev
}