kot.pink
advent of code 2025
day 3 part 2
+12
-19
3.py
+12
-19
3.py
···
1
1
import sys
2
-
import heapq
3
2
4
3
output_two = 0
5
4
output_twelve = 0
6
5
file = '3.input' if len(sys.argv) <= 1 else sys.argv[1]
7
6
for line in open(file).readlines():
8
-
first_seen = {} # digit to first index
9
-
last_seen = {} # digit to last index
10
-
for i, digit in enumerate(line.strip()):
11
-
first_seen.setdefault(int(digit), i)
12
-
last_seen[int(digit)] = i
13
-
14
-
max_all = max(first_seen.keys()) # largest digit (always included)
15
-
if last_seen[max_all] > first_seen[max_all]: # if it appears twice, just use it
16
-
output_two += max_all * 11
17
-
continue
7
+
line = line.strip()
8
+
for n in [2, 12]:
9
+
result = [-1] * n
10
+
for it in range(n):
11
+
right = list(enumerate(line[:-(n-1)+it or len(line)]))
12
+
allowed = [(i, d) for i, d in right if i > max(result)]
13
+
pick = max(allowed, key=lambda a: a[1])
14
+
result[it] = pick[0]
18
15
19
-
try:
20
-
# first search right of the max digit
21
-
max_right = max(digit for digit, i in last_seen.items() if i > first_seen[max_all])
22
-
output_two += max_all * 10 + max_right
23
-
except ValueError:
24
-
# search left for max digit
25
-
max_left = max(digit for digit, i in last_seen.items() if i < first_seen[max_all])
26
-
output_two += max_left * 10 + max_all
16
+
if n == 2:
17
+
output_two += int("".join(line[i] for i in result))
18
+
elif n == 12:
19
+
output_twelve += int("".join(line[i] for i in result))
27
20
28
21
print(f'p1: {output_two}')
29
22
print(f'p2: {output_twelve}')