with open('data-2023-03.txt', 'r') as f:
inp = f.read().splitlines()
len(inp)
len(inp[0])140Advent of Code 2023 Day 3
— Day 3: Gear Ratios —
We need to fix the gondola with a part schematic. Any number adjacent to a symbol, even diagonally, is a “part number” and should be included in your sum. (Periods (.) do not count as a symbol.)
What is the sum of all of the part numbers in the engine schematic?
Let’s find the possible symbols, that should be easier than regex, maybe?
# here's another python cell for good luck
charact = ''.join(inp)
sc = sorted(list(set(charact)))
sc
remover = '.0123456789'
sym = [i for i in sc if i not in remover]
sym
num = remover[1:]
num'0123456789'Create an array with the schematic input, but we want to have . characters on the outside so that we can loop more easily i.e. not have to worry if we’re on an edge.
import numpy as np
import itertools
# array full of dots
arr = np.full((142, 142), '.')
# list of lists
inp_char = [list(x) for x in inp]
# put the input into the array
arr[1:141, 1:141] = inp_char
# check
# arr[1, 59]summer = 0
i = 0
while i < arr.shape[1]:
j = 0
while j < arr.shape[0]:
# reset these through each loop
sym_found = False
curr_num = ''
# test the current character
if arr[i,j] == '.':
# do nothing
j += 1
elif arr[i,j] in sym:
# do nothing
j += 1
elif arr[i,j] in num:
# record the number
curr_num += arr[i,j]
# print(arr[i,j])
# search for symbols
for m,n in itertools.product([-1, 0, 1], [-1, 0, 1]):
if arr[i+m,j+n] in sym:
sym_found = True
# increase the position in our row
j += 1
if arr[i,j] in num:
curr_num += arr[i,j]
for m,n in itertools.product([-1, 0, 1], [-1, 0, 1]):
if arr[i+m,j+n] in sym:
sym_found = True
# increase row position again
j += 1
if arr[i,j] in num:
curr_num += arr[i,j]
for m,n in itertools.product([-1, 0, 1], [-1, 0, 1]):
if arr[i+m,j+n] in sym:
sym_found = True
# increase row position again
j += 1
# if there is a symbol, add the number to the sum
if sym_found == True:
summer += int(curr_num)
# print(curr_num)
# iterate i when we reach the end of j
i += 1
summer539433— Part Two —
A gear is any * symbol that is adjacent to exactly two part numbers. Its gear ratio is the result of multiplying those two numbers together.
What is the sum of all of the gear ratios in your engine schematic?
Now we are looking for all of the * symbols and checking for surrounding numbers. We need to be more careful since we are looking for exactly two adjacent strings of numbers, so we need to know where those numbers start and finish.
# change symbol input, we actually only care about the * now
sym = '#$%&+-/=@'
summer = 0
i = 0
while i < arr.shape[1]:
j = 0
while j < arr.shape[0]:
# reset these through each loop
nf = ''
row_above = False
row_below = False
# test the current character
if arr[i,j] == '.' or arr[i,j] in sym or arr[i,j] in num:
# do nothing
j += 1
elif arr[i,j] == '*':
# we have found a gear if we have also found two numbers.
# in the row above and below, we could go from j-3 to j+3
# there could also be two numbers in that range
# in the same row as * we have j-3 to j+3
# but we know those are different numbers
# look to the left of the *
if arr[i,j-1] in num:
if arr[i,j-2] in num:
if arr[i,j-3] in num:
nf += arr[i,j-3] + arr[i,j-2] + arr[i,j-1] + ' '
else:
nf += arr[i,j-2] + arr[i,j-1] + ' '
else:
nf += arr[i,j-1]
# look to the right of the *
if arr[i,j+1] in num:
if arr[i,j+2] in num:
if arr[i,j+3] in num:
nf += arr[i,j+1] + arr[i,j+2] + arr[i,j+3] + ' '
else:
nf += arr[i,j+1] + arr[i,j+2] + ' '
else:
nf += arr[i,j+1] + ' '
# look above the *
if arr[i-1,j] in num:
# backwards then forwards
row_above = True
if arr[i-1,j-1] in num:
if arr[i-1,j-2] in num:
nf += arr[i-1,j-2] + arr[i-1,j-1] + arr[i-1,j] + ' '
else:
if arr[i-1,j+1] in num:
nf += arr[i-1,j-1] + arr[i-1,j] + arr[i-1,j+1] + ' '
else:
nf += arr[i-1,j-1] + arr[i-1,j] + ' '
else:
if arr[i-1,j+1] in num:
if arr[i-1,j+2] in num:
nf += arr[i-1,j] + arr[i-1,j+1] + arr[i-1,j+2] + ' '
else:
nf += arr[i-1,j] + arr[i-1,j+1] + ' '
else:
nf += arr[i-1,j] + ' '
# look up and left
if not row_above and arr[i-1,j-1] in num:
# look backwards
if arr[i-1,j-2] in num:
if arr[i-1,j-3] in num:
nf += arr[i-1,j-3] + arr[i-1,j-2] + arr[i-1,j-1] + ' '
else:
nf += arr[i-1,j-2] + arr[i-1,j-1] + ' '
else:
nf += arr[i-1,j-1] + ' '
# look up and right
if not row_above and arr[i-1,j+1] in num:
# look forwards
if arr[i-1,j+2] in num:
if arr[i-1,j+3] in num:
nf += arr[i-1,j+1] + arr[i-1,j+2] + arr[i-1,j+3] + ' '
else:
nf += arr[i-1,j+1] + arr[i-1,j+2] + ' '
else:
nf += arr[i-1,j+1] + ' '
# look below the *
if arr[i+1,j] in num:
# backwards then forwards
row_below = True
if arr[i+1,j-1] in num:
if arr[i+1,j-2] in num:
nf += arr[i+1,j-2] + arr[i+1,j-1] + arr[i+1,j] + ' '
else:
if arr[i+1,j+1] in num:
nf += arr[i+1,j-1] + arr[i+1,j] + arr[i+1,j+1] + ' '
else:
nf += arr[i+1,j-1] + arr[i+1,j] + ' '
else:
if arr[i+1,j+1] in num:
if arr[i+1,j+2] in num:
nf += arr[i+1,j] + arr[i+1,j+1] + arr[i+1,j+2] + ' '
else:
nf += arr[i+1,j] + arr[i+1,j+1] + ' '
else:
nf += arr[i+1,j] + ' '
if not row_below and arr[i+1,j-1] in num:
# look backwards
if arr[i+1,j-2] in num:
if arr[i+1,j-3] in num:
nf += arr[i+1,j-3] + arr[i+1,j-2] + arr[i+1,j-1] + ' '
else:
nf += arr[i+1,j-2] + arr[i+1,j-1] + ' '
else:
nf += arr[i+1,j-1] + ' '
if not row_below and arr[i+1,j+1] in num:
# look forwards
if arr[i+1,j+2] in num:
if arr[i+1,j+3] in num:
nf += arr[i+1,j+1] + arr[i+1,j+2] + arr[i+1,j+3] + ' '
else:
nf += arr[i+1,j+1] + arr[i+1,j+2] + ' '
else:
nf += arr[i+1,j+1] + ' '
# now do something with this information
# print(nf)
yy = nf.split()
if len(yy) == 2:
summer += int(yy[0]) * int(yy[1])
j += 1
# iterate i when we reach the end of j
i += 1
summer75847567First answer: 64,491,217 (too low)
Second: 24,397,395 (too low)
Third: 75,847,567 (gold star)