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03_spiral.py
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03_spiral.py
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import itertools
from collections import defaultdict
def move_right(x,y): return x+1, y
def move_down(x,y): return x,y-1
def move_left(x,y): return x-1,y
def move_up(x,y): return x,y+1
def spiral(end):
m = itertools.cycle([move_right, move_up, move_left, move_down])
n = 1
pos = 0,0
times_to_move = 1
yield n, pos
while True:
for _ in range(2):
move = next(m)
for _ in range(times_to_move):
if n >= end:
return
pos = move(*pos)
n += 1
yield n, pos
times_to_move += 1
def get_sum_neighbors(d, pos):
s = 0
for n in [(1,0), (1,1), (0,1), (-1,1), (-1,0), (-1,-1), (0,-1), (1,-1)]:
idx = (pos[0]+n[0], pos[1]+n[1])
s += d[idx]
return s
# Part One
puzzle_input = 347991
sp = spiral(puzzle_input)
try:
while True:
n, pos = next(sp)
except StopIteration:
pass
print(abs(pos[0]) + abs(pos[1]))
# Part Two
sp = spiral(puzzle_input)
s = defaultdict(lambda: 0)
s[(0,0)] = 1
next(sp)
while True:
_, pos = next(sp)
v = get_sum_neighbors(s, pos)
if v > puzzle_input:
print(v)
break
s[pos] = v