In-place Reversal Linked List

Iterative

def reverse(start: Node) -> Node:
	curr = start
	previous = None
	
	while curr:
		next = curr.next
		curr.next = previous
		previous = curr
		curr = next

	return previous

class Node:
	__slots__ = ['next', 'value']
	
	def __init__(self, value: int):
		self.value = value
		self.next = None

Recursive

class App:
    def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]:
        if not head: return
        
        nextHead = head
        if head.next:
            nextHead = self.reverseList(head.next)
            head.next.next = head
        
        head.next = None

        return nextHead