https://www.reddit.com/r/dailyprogrammer/comments/4rug59/20160708_challenge_274_hard_loop_solver/

loops.py

class Node:
	def __init__(self, val):
		self.up = bool(val & 1)
		self.right = bool(val & 2)
		self.down = bool(val & 4)
		self.left = bool(val & 8)
	def rotate(self):
		self.up, self.right, self.down, self.left = self.right, self.down, self.left, self.up
	def num(self):
		return self.up<<0 | self.right<<1 | self.down<<2 | self.left<<3

lines = open("input.txt").read().strip().splitlines()
lines = [[Node(int(x)) for x in line.split()] for line in lines]
flat = [x for row in lines for x in row]

edge = Node(0)
for y, row in enumerate(lines):
	for x, node in enumerate(row):
		node.node_up   = lines[y-1][x] if y != 0 else edge
		node.node_left = lines[y][x-1] if x != 0 else edge
		node.is_edge_down  = y == len(lines)-1
		node.is_edge_right = x == len(row)-1

def check(node):
	if node.up != node.node_up.down:
		return False
	if node.left != node.node_left.right:
		return False
	if node.is_edge_down and node.down:
		return False
	if node.is_edge_right and node.right:
		return False
	return True

def recurse(n):
	if n == len(flat):
		return True
	for i in range(4):
		if check(flat[n]):
			if recurse(n+1):
				return True
		flat[n].rotate()

recurse(0)
chars = ' ╹╺┗╻┃┏┣╸┛━┻┓┫┳╋'
for y, row in enumerate(lines):
	print(''.join(chars[node.num()] for node in row))
for y, row in enumerate(lines):
	print(' '.join(str(node.num()) for node in row))