LeetCode - Reverse Linkedlist

reverse_linkedlist

# Definition for singly-linked list.
# class ListNode
#     attr_accessor :val, :next
#     def initialize(val)
#         @val = val
#         @next = nil
#     end
# end

# @param {ListNode} head
# @return {ListNode}
def reverse_list(head)
    node_length = list_node_length(head)
    counter = 0
    
    while counter_x < node_length
        swap_list(head, node_length - 1, counter)   
        counter_x += 1
    end
    
    head
end


def swap_list(current_node, node_length, count)
    return current_node if node_length == count
    
    if !current_node.next.nil?
        temp_val = current_node.val
        current_node.val = current_node.next.val
        current_node.next.val = temp_val
        count += 1
        swap_list(current_node.next, node_length, count)
    end
end

def linkedlist_length(head, count = 0)
    return count if head.nil?

    count += 1
    list_node_length(head.next, count)
end