My Advent of Code solutions in Python.
kevinyap.ca/2019/12/going-fast-in-advent-of-code/
advent-of-code
python
Add 2025/05
+65
+65
2025/day05.py
+65
2025/day05.py
···
1
+
import fileinput
2
+
3
+
4
+
def is_fresh(ingredient, intervals):
5
+
for a, b in intervals:
6
+
if a <= ingredient <= b:
7
+
return True
8
+
9
+
return False
10
+
11
+
12
+
def is_overlap(a, b, c, d):
13
+
"""Returns the (min, max) if (a, b) and (c, d) overlap, else None."""
14
+
if a <= c <= d <= b:
15
+
return a, b
16
+
elif c <= a <= b <= d:
17
+
return c, d
18
+
elif c <= b <= d and a <= c <= b:
19
+
return a, d
20
+
21
+
return None, None
22
+
23
+
24
+
def merge_intervals(intervals):
25
+
def _merge_one_pass(intervals):
26
+
new_intervals = []
27
+
28
+
for y in range(len(intervals)):
29
+
for x in range(len(intervals)):
30
+
if x == y:
31
+
continue
32
+
33
+
a, b = intervals[x]
34
+
c, d = intervals[y]
35
+
m, n = is_overlap(a, b, c, d)
36
+
37
+
if m is not None and n is not None:
38
+
new_intervals = [interval for i, interval in enumerate(intervals) if i != x and i != y]
39
+
new_intervals.append((m, n))
40
+
return new_intervals
41
+
42
+
return intervals
43
+
44
+
while True:
45
+
new_intervals = _merge_one_pass(intervals)
46
+
if len(new_intervals) == len(intervals):
47
+
return intervals
48
+
intervals = new_intervals
49
+
50
+
51
+
# Read problem input.
52
+
INTERVALS = []
53
+
INGREDIENTS = []
54
+
for line in fileinput.input():
55
+
line = line.strip()
56
+
if '-' in line:
57
+
a, b = line.split('-')
58
+
INTERVALS.append((int(a), int(b)))
59
+
elif line:
60
+
INGREDIENTS.append(int(line))
61
+
62
+
# Solve problem.
63
+
INTERVALS = merge_intervals(INTERVALS)
64
+
print("Part 1:", sum(is_fresh(ingredient, INTERVALS) for ingredient in INGREDIENTS))
65
+
print("Part 2:", sum(b - a + 1 for a, b in INTERVALS))