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day 3 refactor + comments

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magical 2025-12-03 06:17:14 +00:00
parent ecbbd39af1
commit 2cc595523d
1 changed files with 16 additions and 7 deletions
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23
day03/sol.py
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@ -1,15 +1,24 @@
input = open("input") input = open("input")
part1 = 0 part1 = 0
part2 = 0 part2 = 0
shift = [0] + [10**i for i in range(12)]
for line in input: for line in input:
cells = list(line.strip()) digits = list(line.strip())
cells.reverse() # max[n] is the value of the maximal n digit subsequence
max = ["0"*i for i in range(12+1)] max = [0] * 13
for (k,c) in enumerate(cells): # iterate over the digits in least-significant to most-significant order.
# k is the number of digits already processed.
for (k,c) in enumerate(reversed(digits)):
c = int(c)
# the maximal n-digit subsequence we can make that starts with the
# current digit (c) is equal to the concatenation of c and the
# maximal (n-1)-digit subsequence.
# if that's more than the best value we've seen so far, update max[n].
# we have to update max in reverse order in order to avoid reusing digits.
for i in reversed(range(1,min(k+2,len(max)))): for i in reversed(range(1,min(k+2,len(max)))):
j = c+max[i-1] joltage = c*shift[i] + max[i-1]
if j > max[i]: if joltage > max[i]:
max[i] = j max[i] = joltage
#print(max[12]) #print(max[12])
part1 += int(max[2]) part1 += int(max[2])
part2 += int(max[12]) part2 += int(max[12])