Solution: Square Tiles(Google Code Jam 2011 Round 1C Problem A)

st.py

import sys

# files
fin = file(sys.argv[1])
fout = open(sys.argv[2], 'w')
lines = fin.readlines()
tests = int(lines[0])

# parse
indexes = [1]
wh = []
for i in range(tests):
	wh.append(map(int, lines[indexes[i]].split()))
	indexes.append(indexes[i] + wh[i][0] + 1)

# tiles
tiles = [] 
for i in range(tests):
	index = indexes[i]
	h = wh[i][0]
	# w = wh[i][1]
	tile = {}
	for j in range(h):
		tile[j] = lines[index + j + 1].split()
	tiles.append(tile)

# switch
def blue(c0):
	if c0 == '#':
		return True
	return False

def get(x0, y0, t0):
	r0 = None
	try:
		r0 = t0[y0][0][x0]
	except ValueError:
		r0 = None
	finally:	
		return r0

def quad(x0, y0, t0):
	xy = [(x0,y0),(x0+1,y0),(x0,y0+1),(x0+1,y0+1)] 
	q0 = []
	for p0 in xy:
		q0.append(get(p0[0],p0[1],t0))
	return q0	

def switch(x0, y0, t0):
	q0 = quad(x0, y0, t0)
	if len(filter(lambda x: x, map(blue, q0))) == 4:
		r0 = list(t0[y0][0])
		r1 = list(t0[y0+1][0])
		""" python str immutable
		t0[y0][0][x0] = '/'
		t0[y0][0][x0+1] = '\\'
		t0[y0+1][0][x0] = '\\'
		t0[y0+1][0][x0+1] = '/'
		"""
		r0[x0] = '/'
		r0[x0+1] = '|' # backslash hack ;)
		r1[x0] = '|'
		r1[x0+1] = '/'
		t0[y0][0] = "".join(r0)
		t0[y0+1][0] = "".join(r1)

def output(t0, c0):
	fout.write("Case #%d:\n" % c0)
	imp = False
	for y in t:
		for x in range(len(t[y][0])): 
			if blue(t[y][0][x]):
				imp = True
				break
		else:
			continue
		break	
	if (imp):
		fout.write("Impossible")
	else:
		for y in t:
			for x in range(len(t[y][0])):
				if t[y][0][x] == '|':
					fout.write('\\')
				else:
					fout.write(t[y][0][x])
			fout.write('\n')
	fout.write('\n')	

c = 1
for t in tiles:
	for y in t:
		for x in range(len(t[y][0])): 
			if blue(t[y][0][x]):
				switch(x, y, t)
	output(t, c)
	c += 1