skryl

def min_len(a)
  h = Hash.new { |h,k| h[k] = [] }
  a.each.with_object(h)
       .with_index { |(i, h), idx| h[i] << idx }
       .values.map { |a| [a.size, a.last - a.first] }
       .sort       { |i1, i2| [i1.first, i1.last] <=> [i2.first, i2.last] }
       .last.last
end

def min_len(a)

skryl

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example:

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.

skryl

def lev(s, t)
  return t.size if s.empty?
  return s.size if t.empty?
  sc, tc = s.chop, t.chop

  if s[-1] == t[-1]
    return lev(sc, tc)
  end

  return [ lev(sc, t) + 1,  # remove