import numpy as np
with open('data-2023-13.txt', 'r') as f:
inp = f.read().split('\n\n')Advent of Code 2023 Day 13
— Day 13: Point of Incidence —
We are now on Lava Island, but there isn’t any lava. There is lots of ash and rock, and some mirrors, which makes things confusing.
Find the line of reflection in each of the patterns in your notes. What number do you get after summarizing all of your notes?
It’s not enough to just match two consecutive rows or columns, we need to iterate outwards from each pair that matches. Two consecutive rows the same is a candidate for point of reflection, but not sufficient.
Let’s assume that three rows or columns matching is sufficient, or if we do not have enough to check, then that is the match.
mirr0 = [j.split('\n') for j in inp]
# loop through and collect
mirr = [np.array([list(i) for i in m]) for m in mirr0]
# len(mirr)
# mirr[3]
for m in mirr:
fndr = 0
fndc = 0
found = False
for j in range(len(m)-1):
if found:
break
for p,q in zip([0,1,2,3], [1,2,3,4]):
if found:
break
if j-p >= 0 and j+q < len(m):
if list(m[j-p]) == list(m[j+q]):
fndr += 1
found = True
# print(j, p, q, "mirror")
else:
# this should get us out if it does not match
break
else:
# we are out of bounds, and assuming that we have a match
# there is no way to disprove a match?
fndr += 1
found = True
# print(j, p, q, "edge")
for k in range(len(m[0])-1):
for p,q in zip([0,1,2,3], [1,2,3,4]):
if k-p >= 0 and k+q < len(m[0]):
if list(m[:,k-p]) == list(m[:,k+q]):
found = True
# keep looking
else:
# this should get us out if something does not match
break
else:
if found == True:
# we've found at least one match
fndc += 1
break
# we have gone through the list without a break
fndc += 1
break
# print(fndr, fndc)That’s not really working, let’s go back to what I started with which explicitly lists the row differences
mirr0 = [j.split('\n') for j in inp]
mirr = [np.array([list(i) for i in m]) for m in mirr0]
for m in mirr:
fndr = 0
fndc = 0
for j in range(len(m)-1):
if list(m[j]) == list(m[j+1]):
if j-1 >= 0 and j+2 < len(m):
if list(m[j-1]) == list(m[j+2]):
if j-2 >= 0 and j+3 < len(m):
if list(m[j-2]) == list(m[j+3]):
if j-3 >= 0 and j+4 < len(m):
if list(m[j-3]) == list(m[j+4]):
if j-4 >= 0 and j+5 < len(m):
if list(m[j-4]) == list(m[j+5]):
fndr += 1
else:
fndr += 1
else:
fndr += 1
else:
fndr += 1
else:
fndr += 1
for k in range(len(m[0])-1):
if list(m[:,k]) == list(m[:,k+1]):
if k-1 >= 0 and k+2 < len(m[0]):
if list(m[:,k-1]) == list(m[:,k+2]):
if k-2 >= 0 and k+3 < len(m[0]):
if list(m[:,k-2]) == list(m[:,k+3]):
if k-3 >= 0 and k+4 < len(m[0]):
if list(m[:,k-3]) == list(m[:,k+4]):
if k-4 >= 0 and k+5 < len(m[0]):
if list(m[:,k-4]) == list(m[:,k+5]):
fndc += 1
else:
fndc += 1
else:
fndc += 1
else:
fndc += 1
else:
fndc += 1
# print(fndr, fndc)
if fndc == 2:
print(m)[['.' '.' '.' '.' '#' '.' '.' '.' '.' '#' '.' '.' '.' '.' '.']
['.' '.' '#' '#' '#' '.' '.' '.' '.' '#' '#' '#' '.' '.' '.']
['#' '.' '.' '.' '.' '#' '#' '#' '#' '.' '.' '.' '.' '#' '#']
['#' '#' '.' '.' '#' '#' '.' '.' '#' '#' '.' '.' '#' '#' '#']
['#' '#' '#' '.' '.' '#' '.' '.' '#' '.' '.' '#' '#' '.' '.']
['#' '.' '.' '.' '#' '.' '.' '.' '.' '#' '.' '.' '.' '#' '#']
['.' '#' '.' '#' '#' '.' '#' '#' '.' '#' '#' '.' '#' '.' '.']
['#' '#' '#' '#' '#' '#' '.' '.' '#' '#' '#' '#' '#' '#' '#']
['#' '#' '.' '.' '#' '#' '.' '.' '#' '#' '.' '.' '#' '#' '#']
['.' '.' '.' '.' '#' '#' '#' '#' '#' '#' '.' '.' '.' '.' '.']
['#' '#' '#' '.' '#' '#' '.' '.' '#' '#' '.' '#' '#' '#' '#']
['.' '.' '#' '#' '.' '#' '#' '#' '#' '.' '#' '#' '.' '.' '.']
['#' '#' '#' '.' '#' '.' '.' '.' '.' '#' '.' '#' '#' '#' '#']]
[['.' '.' '#' '#' '.' '.' '.' '.' '.' '.' '#' '#' '.']
['.' '.' '#' '#' '.' '.' '#' '#' '.' '.' '#' '#' '.']
['.' '.' '.' '.' '.' '.' '#' '#' '.' '.' '.' '.' '.']
['.' '.' '#' '#' '#' '.' '#' '#' '.' '#' '#' '#' '.']
['.' '.' '#' '#' '#' '.' '.' '.' '.' '#' '#' '#' '.']
['#' '#' '#' '.' '#' '#' '.' '.' '#' '#' '.' '#' '.']
['#' '#' '#' '.' '.' '#' '#' '#' '#' '.' '.' '#' '#']
['#' '#' '#' '.' '.' '.' '.' '.' '.' '.' '.' '#' '#']
['#' '#' '#' '#' '.' '.' '.' '.' '.' '.' '#' '#' '#']]Revelation: we should only set the mirror row / column when we reach the end. This may not be good for the second part but let’s do that for now. There are too many tricky scenarios of almost symmetry!
mirr0 = [j.split('\n') for j in inp]
# loop through and collect
mirr = [np.array([list(i) for i in m]) for m in mirr0]
summer = 0
for m in mirr:
fndr = 0
fndc = 0
# found = False
# print(len(m))
for j in range(len(m)-1):
p = 0
# print('--new row', j)
while p < 99:
if j-p >= 0 and j+p+1 < len(m):
# print('checking', p)
if list(m[j-p]) == list(m[j+p+1]):
# print('some match', p)
p += 1
else:
# this should get us out if it does not match
# print('no match')
break
else:
# we are out of bounds, and assuming that we have a match
# print('found it')
fndr += 1
summer += 100 * (j+1)
break
for k in range(len(m[0])-1):
p = 0
while p < 99:
if k-p >= 0 and k+p+1 < len(m[0]):
if list(m[:,k-p]) == list(m[:,k+p+1]):
p += 1
else:
break
else:
fndc += 1
summer += (k+1)
break
# show the results
# print(fndr, fndc)
summer 27505— Part Two —
There are smudges on the mirrors! On each mirror there is one smudge, that needs to change . to # or # to . and there is a new line of reflection.
In each pattern, fix the smudge and find the different line of reflection. What number do you get after summarizing the new reflection line in each pattern in your notes?