StyleInCode

""" day_06_01.py """

# usage: python3 day_06_01.py < input

import sys


def on_map(loc, across, down):
    """ is loc within across by down """
    if loc[0] in range(across) and loc[1] in range(down):
        return True
    return False


def step(loc, way, objects):
    """ take a step or turn to avoid obstruction """
    new = loc[0] + way[0], loc[1] + way[1]
    if new in objects:
        headings = [(0, -1), (1, 0), (0, 1), (-1, 0)]
        return loc, headings[(headings.index(way) + 1) % 4]
    return new, way


width, height = None, None
pos, bearing = None, None
obstructions = []

with sys.stdin as infile:
    for j, line in enumerate(infile):
        for i, x in enumerate(line.strip()):
            if x == '#':
                obstructions.append((i, j))
            elif x == '^':
                pos, bearing = (i, j), (0, -1)
            width = i + 1
        height = j + 1

visited = set()
while on_map(pos, width, height):
    visited.add(pos)
    pos, bearing = step(pos, bearing, obstructions)

print(len(visited))

""" day_06_02.py """

# usage: python3 day_06_02.py < input

import sys


def on_map(loc, across, down):
    """ is loc within across by down """
    if loc[0] in range(across) and loc[1] in range(down):
        return True
    return False


def step(loc, way, objects):
    """ take a step or turn to avoid obstruction """
    new = loc[0] + way[0], loc[1] + way[1]
    if new in objects:
        headings = [(0, -1), (1, 0), (0, 1), (-1, 0)]
        return loc, headings[(headings.index(way) + 1) % 4]
    return new, way


width, height = None, None
start = None
obstructions = []

with sys.stdin as infile:
    for j, line in enumerate(infile):
        for i, x in enumerate(line.strip()):
            if x == '#':
                obstructions.append((i, j))
            elif x == '^':
                start = ((i, j), (0, -1))
            width = i + 1
        height = j + 1

loops = 0
for j in range(height):
    for i in range(width):
        if (i, j) in obstructions or (i, j) == start[0]:
            continue
        obstructions.append((i, j))
        visited = set()
        pos, bearing = start
        while on_map(pos, width, height):
            visited.add((pos, bearing))
            pos, bearing = step(pos, bearing, obstructions)
            if (pos, bearing) in visited:
                loops += 1
                break
        obstructions.pop()

print(loops)