Non-working solution for day 14 part 2 of AoC 2021

aoc_2021_day_14_part_2.py

import collections
import numpy as np


template, insertions = open("../../input/day_14_example.txt").read().split("\n\n")
insertions = insertions.split("\n")
rules = {}
rules_idx = {}

for i, insertion in enumerate(insertions):
    split_insertion = insertion.rstrip().split(" -> ")
    rules[split_insertion[0]] = split_insertion[1]
    rules_idx[split_insertion[0]] = i

n = len(rules)
x = np.zeros(n)
A = np.zeros((n, n))

bigrams = [template[i:i+2] for i in range(len(template) - 1)]

for bigram in bigrams:
    x[rules_idx[bigram]] += 1

for rule in rules_idx:
    r = list(rule)
    r.insert(1, rules[rule])
    
    trigram = "".join(c for c in r)
    
    b1 = trigram[:2]
    b2 = trigram[1:]
    
    col_1 = rules_idx[b1]
    col_2 = rules_idx[b2]
    A[rules_idx[rule], col_1] = 1
    A[rules_idx[rule], col_2] = 1
    
b = np.dot(x, np.linalg.matrix_power(A, 10))
res = template[0] + template[-1]

keys = list(rules_idx.keys())
# vals = list(rules_idx.values())
for i in range(n):
    res += int(b[i]) * keys[i]
    
#res += template[-1]
char_count = collections.Counter(res).most_common()

most_common = char_count[0]
least_common = char_count[-1]

print(most_common)
print(least_common)
print("difference", most_common[1] - least_common[1])