Day 6: Guard Gallivant

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
  • You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

  • TunaCowboy@lemmy.world
    2·
    23 days ago

    python

    Takes around 10s on my machine. I came up 10 short at first for part two and then realized sometimes you have to turn multiple times to avoid an obstacle.

    solution 
    from dataclasses import dataclass
import aoc

@dataclass
class Guard():
    r: int = 0
    c: int = 0
    d: str = 'n'

    def move(self, lines):
        for _ in range(4):
            if self.d == 'n':
                if lines[self.r - 1][self.c] == '#':
                    self.d = 'e'
                else:
                    self.r -= 1
                    break
            elif self.d == 'e':
                if lines[self.r][self.c + 1] == '#':
                    self.d = 's'
                else:
                    self.c += 1
                    break
            elif self.d == 's':
                if lines[self.r + 1][self.c] == '#':
                    self.d = 'w'
                else:
                    self.r += 1
                    break
            elif self.d == 'w':
                if lines[self.r][self.c - 1] == '#':
                    self.d = 'n'
                else:
                    self.c -= 1
                    break

def setup():
    lines = aoc.get_lines(6, padded=(True, 'X', 1))
    g = Guard()
    for row, l in enumerate(lines):
        for col, c in enumerate(l):
            if c == '^':
                g.r, g.c = (row, col)
    s = (g.r, g.c)
    p = set()
    while lines[g.r][g.c] != 'X':
        p.add((g.r, g.c))
        g.move(lines)
    return (lines, g, s, p)

def one():
    print(len(setup()[3]))

def two():
    lines, g, s, p = setup()
    acc = 0
    for r, c in p:
        t = list(lines)
        ts = list(t[r])
        ts[c] = '#'
        t[r] = ''.join(ts)
        g.r, g.c, g.d = (s[0], s[1], 'n')
        v = set()
        while t[g.r][g.c] != 'X':
            st = (g.r, g.c, g.d)
            if st in v:
                acc += 1
                break
            v.add(st)
            g.move(t)
    print(acc)

one()
two()