54 lines
868 B
Python
54 lines
868 B
Python
|
#!/usr/bin/env python3
|
||
|
|
|
||
|
|
import aoc
|
||
|
|
import math
|
||
|
|
import itertools
|
||
|
|
|
||
|
|
|
||
|
|
# https://stackoverflow.com/questions/10094745
|
||
|
|
def spiralpos(n):
|
||
|
|
k = math.ceil((math.sqrt(n) - 1) / 2)
|
||
|
|
t = 2 * k + 1
|
||
|
|
m = t ** 2
|
||
|
|
|
||
|
|
t -= 1
|
||
|
|
|
||
|
|
if n >= m - t:
|
||
|
|
return k - (m - n), -k
|
||
|
|
|
||
|
|
m -= t
|
||
|
|
|
||
|
|
if n >= m - t:
|
||
|
|
return -k, -k + (m - n)
|
||
|
|
|
||
|
|
m -= t
|
||
|
|
|
||
|
|
if n >= m - t:
|
||
|
|
return -k + (m - n), k
|
||
|
|
|
||
|
|
return k, k - (m - n - t)
|
||
|
|
|
||
|
|
|
||
|
|
rawinput = aoc.read_input(3)
|
||
|
|
intinput = int(rawinput)
|
||
|
|
|
||
|
|
dirs = [
|
||
|
|
(-1, -1), (00, -1), (+1, -1),
|
||
|
|
(-1, 00), (+1, 00),
|
||
|
|
(-1, +1), (00, +1), (+1, +1),
|
||
|
|
]
|
||
|
|
|
||
|
|
grid = dict()
|
||
|
|
grid[(0, 0)] = 1
|
||
|
|
|
||
|
|
for i in itertools.count(2):
|
||
|
|
x, y = spiralpos(i)
|
||
|
|
v = 0
|
||
|
|
for dx, dy in dirs:
|
||
|
|
if (x + dx, y + dy) in grid:
|
||
|
|
v += grid[(x + dx, y + dy)]
|
||
|
|
if v > intinput:
|
||
|
|
print(v)
|
||
|
|
exit()
|
||
|
|
grid[(x, y)] = v
|