AdventOfCode/2020/day10.py
2020-12-10 22:43:00 +01:00

35 lines
723 B
Python

import sys
def main():
lines = sorted([int(line.rstrip()) for line in sys.stdin])
# Part 1
diffs = {1: 0, 3: 0}
jojo = 0
for v in lines:
d = v - jojo
diffs[d] += 1
jojo = v
print("Part 1:", diffs[1] * (diffs[3] + 1))
# Part 2 - yes recursion is fine but have you tried caching your damn values
print("Part 2:", rec(0, lines, 0, len(lines), {}))
def rec(i, l, n, z, c):
if i >= z - 1:
return 1
if (p := c.get((i, n))) is not None:
return p
p = 0
for ni, nv in enumerate(l[i:i+3]):
if n < nv <= n + 3:
p += rec(i + ni + 1, l, nv, z, c)
c[(i, n)] = p
return p
if __name__ == "__main__":
main()