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Advent of Code 2021 Python Solution: Day 14

#adventofcode #algorithms #python

They know we could fall into a trap. And again I fell. I went full looping mode and got the result of part 1 but the part 2 could take days.

Part 1 

from collections import Counter
data,data1 = get_data(day=14)

wdata=data1.copy()
polymer = wdata[0]
rule = {v[0]:v[1] for v in [d.split(" -> ") for d in wdata[2:]]}

curr_polymer = polymer
i=0
while i< 10:
    tpoly = curr_polymer
#     print(i, tpoly)
    ind = 0
    added = 0
    for k, c in enumerate(tpoly):
        k+=1
        ch = curr_polymer[k-1:k+1]

        mc = rule.get(ch)
        if mc:
            tpoly = [c for c in tpoly]
            tpoly.insert(k+added, mc)
            tpoly = "".join(tpoly)
            added+=1
    curr_polymer = tpoly
    i+=1

res = dict(Counter(curr_polymer))
res = sorted(res.items(), key=lambda x: x[1], reverse=True)
res[0][1]-res[-1][1]
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Part 2

Taken hint from here.

tmp_poly = Counter(a+b for a,b in zip(polymer, polymer[1:]))
print(tmp_poly)
chars = Counter(polymer)

for _ in range(40):
    tmp = Counter()
    for (c1,c2),value in tmp_poly.items():
        mc = rule[c1+c2]
        tmp[c1+mc] += value
        tmp[mc+c2] += value
        chars[mc] += value
    tmp_poly=tmp
max(chars.values()) - min(chars.values())
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