def part_a(data):
seen = set()
grid = ZGrid(data)
while True:
k = tuple(grid.items())
if k in seen:
return sum(2**i for i, glyph in enumerate(grid.values())
if glyph == "#")
seen.add(k)
evolve_a(grid)
grid = ZGrid()
x0 = 0
for y in range(50):
on = False
for x in range(x0, 50):
z = x + y*1j
val = grid[z] = beam(z)
if not on and val:
on = True
x0 = x
if x0:
m = y / x0
if on and not val:
break
grid.draw()
print("part a", sum(grid.values()))
def left_edge_of_beam(y, gradient):
x = int(y / gradient)
z = x + y*1j
if beam(z):
while beam(z - 1):
z -= 1
else:
while not beam(z + 1):
z += 1
z += 1
assert beam(z) and not beam(z - 1)
return z