lol.rb

# Definition for singly-linked list:
# class ListNode
#   attr_accessor :value, :next
#   def initialize(val)
#     @value = val
#     @next = nil
# end
#
def isListPalindrome(l)
    offset = -1
    curr = l
    while curr
        offset += 1
        curr = curr.next
    end
    
    tracker = {}
    
    pos = 0
    curr = l
    while curr
        tracker[curr.value] ||= 0
        tracker[curr.value] = tracker[curr.value] ^ (pos-offset).abs
        pos += 2
        curr = curr.next
    end
    puts tracker
    return !tracker.any? do |k, v|
        v != 0
    end
end