Problem p03263 (python)

Fixed submission:
#!/usr/bin/python
# -*- coding: utf-8 -*-

s = raw_input()
H, W = [int(x) for x in s.split()]
# H, W = 500,500
A = [None] * H

for i in xrange(H):
	s = raw_input()
	A[i] = [int(x) for x in s.split()]
	# A[i] = [j for j in xrange(W)]

choose = [[False]*W for i in xrange(H)]
answer = -1
answerOps = []
ops = []

def dfs(y, x, even):
	global H, W, A, answer, answerOps, ops

	if x >= W:
		x, y = 0, y+1
	if x == 0 and y == H:
		if even > answer:
			answer = even
			answerOps = ops
		return
	if even + (H-y-1)*W + (W-x) <= answer:
		return

	# print y, x, A[y][x], even
	# print A

	coin = A[y][x]
	if coin % 2 == 1:
		A[y][x] = 0
		if x+1 < W:
			A[y][x+1] += coin
			ops.append((y, x, y, x+1))
			dfs(y, x+1, even+1)
			ops = ops[:-1]
			A[y][x+1] -= coin

		if y+1 < H:
			A[y+1][x] += coin
			ops.append((y, x, y+1, x))
			dfs(y, x+1, even+1)
			ops = ops[:-1]
			A[y+1][x] -= coin
		A[y][x] = coin

		dfs(y, x+1, even)
	else:
		dfs(y, x+1, even+1)


# dfs(0, 0, 0)


def check(y, x):
	if x+1 < W:
		if A[y][x+1] % 2 == 1:
			return 'right'
	if y+1 < H:
		if A[y+1][x] % 2 == 1:
			return 'down'
	if x+1 < W:
		return 'right'
	if y+1 < H:
		return 'down'

for i in xrange(H):
	for j in range(W):
		if A[i][j] % 2 == 1:
			ret = check(i, j)
			if ret == 'right':
				A[i][j+1] += A[i][j]
				answerOps.append((i, j, i, j+1))
			elif ret == 'down':
				A[i+1][j] += A[i][j]
				answerOps.append((i, j, i+1, j))

print len(answerOps)
for t in answerOps:
	print '%d %d %d %d' % tuple([x+1 for x in t])

Buggy submission (verdict: Runtime Error):
#!/usr/bin/python
# -*- coding: utf-8 -*-

s = raw_input()
H, W = [int(x) for x in s.split()]
A = [None] * H

for i in xrange(H):
	s = raw_input()
	A[i] = [int(x) for x in s.split()]

choose = [[False]*W for i in xrange(H)]
answer = -1
answerOps = []
ops = []

def dfs(y, x, even):
	global H, W, A, answer, answerOps, ops

	if x >= W:
		x, y = 0, y+1
	if x == 0 and y == H:
		if even > answer:
			answer = even
			answerOps = ops
		return
	if even + (H-y-1)*W + (W-x) <= answer:
		return

	# print y, x, A[y][x], even
	# print A

	coin = A[y][x]
	if coin % 2 == 1:
		A[y][x] = 0
		if x+1 < W:
			# print 'right'
			A[y][x+1] += coin
			ops.append((y, x, y, x+1))
			dfs(y, x+1, even+1)
			ops = ops[:-1]
			A[y][x+1] -= coin

		if y+1 < H:
			# print 'down'
			A[y+1][x] += coin
			ops.append((y, x, y+1, x))
			dfs(y, x+1, even+1)
			ops = ops[:-1]
			A[y+1][x] -= coin
		A[y][x] = coin

		dfs(y, x+1, even)
	else:
		dfs(y, x+1, even+1)


dfs(0, 0, 0)
# print answer
# print '----'
print len(answerOps)
for t in answerOps:
	print '%d %d %d %d' % tuple([x+1 for x in t])

Buggy submission (verdict: Runtime Error):
#!/usr/bin/python
# -*- coding: utf-8 -*-

s = raw_input()
H, W = [int(x) for x in s.split()]
A = [None] * H

for i in xrange(H):
	s = raw_input()
	A[i] = [int(x) for x in s.split()]

choose = [[False]*W for i in xrange(H)]
answer = -1
answerOps = []
ops = []

def dfs(y, x, even):
	global H, W, A, answer, answerOps, ops

	if x >= W:
		x, y = 0, y+1
	if x == 0 and y == H:
		if even > answer:
			answer = even
			answerOps = ops
		return
	if even + (H-y-1)*W + (W-x) <= answer:
		return

	# print y, x, A[y][x], even
	# print A

	coin = A[y][x]
	if coin % 2 == 1:
		A[y][x] = 0
		if x+1 < W:
			# print 'right'
			A[y][x+1] += coin
			ops.append((y, x, y, x+1))
			dfs(y, x+1, even+1)
			ops = ops[:-1]
			A[y][x+1] -= coin

		if y+1 < H:
			# print 'down'
			A[y+1][x] += coin
			ops.append((y, x, y+1, x))
			dfs(y, x+1, even+1)
			ops = ops[:-1]
			A[y+1][x] -= coin
		A[y][x] = coin

		dfs(y, x+1, even)
	else:
		dfs(y, x+1, even+1)


dfs(0, 0, 0)
# print answer
# print '----'
print len(answerOps)
for t in answerOps:
	print '%d %d %d %d' % tuple([x+1 for x in t])