aoc-2018-day05-part2.py

#!/usr/bin/env python

import string
from collections import deque

f = open("input.txt", "r")

data = deque()
for char in f.read():
    if char != '\n':
        data.append(char)

def process(inp):
    outp = deque()
    lastC = inp.popleft()
    outp.append(lastC)

    while True:
        # print ("%s-%s" % ("".join(outp), "".join(inp)))
        if not inp:
            break
        c = inp.popleft()
        if (lastC.lower() == c.lower() and ((lastC.isupper() and c.islower()) or (lastC.islower() and c.isupper()))):
                # print ('%s and %s react' % (lastC, c))
                # print ("%s-%s" % ("".join(outp), "".join(inp))))
                if outp:
                    lastC = outp.pop()
                if outp:
                    # rewind
                    inp.appendleft(outp.pop())
        else:
            lastC = c
            outp.append(c)

    return outp

def removeLetter(inp, letter):
    outp = deque()
    inp = inp.copy()
    while True:
        if not inp:
            break
        c = inp.popleft()
        if c.lower() == letter:
            continue
        outp.append(c)
    return outp

newData = process(data)

for c in string.ascii_lowercase:
    print (c, len(process(removeLetter(newData, c))))