Day 15, probably not optimised at all...

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dece 2021-12-16 00:23:08 +01:00
parent 6ac2daf309
commit ead11c9c86

53
2021/day15.py Normal file
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from collections import defaultdict
from math import inf
with open("input15.txt") as f:
lines = [line.rstrip() for line in f]
plan = [list(map(int, line)) for line in lines]
dim = len(plan)
ndim = dim * 5
# wanted to try something other than the yearly djikstra, so overkill and
# incomplete bellman-ford, precedents skipped for laughable gains.
def solve(dimension, risk_f):
dists = defaultdict(lambda: inf)
dists[(0, 0)] = 0
changed = True
while changed:
changed = False
for x in range(dimension):
for y in range(dimension):
p = (x, y)
dist = dists[p]
near = []
if x > 0:
near.append((x - 1, y))
if x < dimension - 1:
near.append((x + 1, y))
if y > 0:
near.append((x, y - 1))
if y < dimension - 1:
near.append((x, y + 1))
for n in near:
nx, ny = n
risk = risk_f(nx, ny)
if dist + risk < dists[n]:
changed = True
dists[n] = dist + risk
return dists
def risk_f1(nx, ny):
return plan[nx][ny]
def risk_f2(nx, ny):
risk = (plan[nx % dim][ny % dim] + nx // dim + ny // dim)
while risk >= 10:
risk -= 9
return risk
print(solve(dim, risk_f1)[(dim - 1, dim - 1)])
print(solve(ndim, risk_f2)[(ndim - 1, ndim - 1)])