def follow_path(map_):
    x, y = map_[0].index("|"), 0
    dx, dy = 0, 1
    steps = 0
    found = []
    while True:
        steps += 1
        x, y = x + dx, y + dy
        mapchar = map_[y][x]
        if mapchar == " " or not 0 <= x < len(map_[0]) or not 0 <= y < len(map_):
            # map end found
            return "".join(found), steps
        if mapchar.isalpha():
            found.append(mapchar)
        elif mapchar == "+":
            # direction change, find new
            if dx:
                dx, dy = 0, 1 if map_[y - 1][x] == " " else -1
            else:
                dx, dy = 1 if map_[y][x - 1] == " " else -1, 0

word, steps = follow_path(
    [
        "     |          ",
        "     |  +--+    ",
        "     A  |  C    ",
        " F---|----E|--+ ",
        "     |  |  |  D ",
        "     +B-+  +--+ ",
    ]
)
assert word == "ABCDEF"
assert steps == 38

import aocd

data = aocd.get_data(day=19, year=2017)
map_ = data.splitlines()