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adventofcode2023
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day 10 more efficient fill 

i also tried getting rid of the 'next' dict and just keeping track of a
boolean of whether we changed anything on each pass, but that made it
slower somehow. cache effects i guess?
main
magical 2023-12-10 07:03:54 +00:00
parent 3ba6804013
commit 3b5b9f3839
1 changed files with 31 additions and 34 deletions
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65
day10/sol.py
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@ -31,13 +31,6 @@ for i, row in enumerate(map):
#print(grid)
def draw(grid):
y = max([i for i,j in grid.keys()])
x = max([j for i,j in grid.keys()])
for i in range(y+1):
print("".join(".+O"[grid[i,j]] if (i,j) in grid else "x" for j in range(x+1)))
print()
def find_loop(grid, start):
front = [(0,start)]
dist = {}
@ -71,57 +64,61 @@ def find_loop(grid, start):
def enclosedby(grid, points):
# upsample by 3x3
fill = {}
for i,j in grid:
for k in range(3):
for l in range(3):
fill[i*3+k,j*3+l] = 0
#print(*sorted(fill.keys()), sep="\n")
fill = [[0]*(X*3) for _ in range(Y*3)]
for i,j in points:
d = grid[i,j]
if d == N|S: t=[[0,1,0],[0,1,0],[0,1,0]]
elif d == N|W: t=[[0,1,0],[1,1,0],[0,0,0]]
elif d == N|E: t=[[0,1,0],[0,1,1],[0,0,0]]
elif d == S|W: t=[[0,0,0],[1,1,0],[0,1,0]]
elif d == S|E:t=[[0,0,0],[0,1,1],[0,1,0]]
elif d == E|W:t=[[0,0,0],[1,1,1],[0,0,0]]
elif d == S|E: t=[[0,0,0],[0,1,1],[0,1,0]]
elif d == E|W: t=[[0,0,0],[1,1,1],[0,0,0]]
else: raise Exception("invalid d=%d at (%s,%s)" % (d, i, j))
for k in range(3):
for l in range(3):
fill[i*3+k,j*3+l] = t[k][l]
#print(fill)
fill[i*3+k][j*3+l] = t[k][l]
def draw(fill):
for row in fill:
print("".join(".+O"[f] for f in row))
draw(fill)
# fill edges
for i in range(Y*3):
if fill[i,0] == 0: fill[i,0] = 2
if fill[i,X*3-1] == 0: fill[i,X*3-1] = 2
if fill[i][ 0 ] == 0: fill[i][ 0 ] = 2
if fill[i][X*3-1] == 0: fill[i][X*3-1] = 2
for j in range(X*3):
if fill[0,j] == 0: fill[0,j] = 2
if fill[Y*3-1,j] == 0: fill[Y*3-1,j] = 2
if fill[ 0 ][j] == 0: fill[ 0 ][j] = 2
if fill[Y*3-1][j] == 0: fill[Y*3-1][j] = 2
# flood fill
next = {}
def set(i,j):
if (i,j) in fill:
if fill[i,j] == 0:
if 0 <= i < Y*3 and 0 <= j < X*3:
if fill[i][j] == 0:
next[i,j] = 2
while True:
#draw(fill)
next = {}
for i,j in fill:
if fill[i,j] == 2:
set(i-1,j)
set(i+1,j)
set(i,j-1)
set(i,j+1)
if not next:
break
fill.update(next)
next.clear()
for i in range(Y*3):
for j in range(X*3):
if fill[i][j] == 2:
set(i-1,j)
set(i+1,j)
set(i,j-1)
set(i,j+1)
if next:
for (i,j),c in next.items():
fill[i][j] = c
continue
break
draw(fill)
# downsample
inside = []
for i,j in grid:
f = [fill[i*3+k,j*3+l]==0 for k in range(3) for l in range(3)]
f = [fill[i*3+k][j*3+l]==0 for k in range(3) for l in range(3)]
if all(f):
inside.append((i,j))