aoc18 day 5 both parts, naive

aoc18_5.py

def react(s):
  stack = [s[0]]
  def push(letter,stack):
    if stack and abs(ord(stack[-1])-ord(letter)) == 32:
      stack.pop()
    else:
      stack.append(letter)

  for letter in s[1:]:
    push(letter,stack)
  return ''.join(stack)

reacted=react(s)

alphabet='qazwsxedcrfvtgbyhnujmiklop'
lens=[]
for letter in alphabet:
  lens.append(len(
    react(
      reacted
      .replace(letter,'')
      .replace(str.upper(letter),''))))
  
  #ans 2 is min(lens)