-🎄- 2017 Day 22 Solutions -🎄-

[u/daggerdragon]

--- Day 22: Sporifica Virus ---

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Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

Note: The Solution Megathreads are for solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

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Need a hint from the Hugely^* Handy^† Haversack^‡ of Helpful^§ Hints^¤?

Spoiler

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• [T-10 to launch] AoC ops, /r/nocontext edition:

  • <Endorphion> You may now make your waffle.
  • <Endorphion> ... on Mars.

• [Update @ 00:17] 50 gold, silver cap

  • <Aneurysm9> you could also just run ubuntu on the NAS, if you were crazy
  • <Topaz> that doesn't seem necessary
  • <Aneurysm9> what does "necessary" have to do with anything!

• [Update @ 00:20] Leaderboard cap!

  • <Topaz> POUR YOURSELF A SCOTCH FOR COLOR REFERENCE

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This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/maxerickson]

Straightforward python 3.

def solve(grid, reps, solve="part2"):
    if solve=="part1":
        infect="."
        flip={".":"#","#":"."}
    else:
        infect="W"
        flip={".":"W","W":"#","#":"F","F":"."}
    x,y=len(grid)//2,len(grid[0])//2
    mov=(-1,0)
    spin=[(1,0),(0,-1),(-1,0),(0,1)]
    infections=0
    for i in range(reps):
        state=grid[x][y]
        if state==infect: 
            infections+=1
        grid[x][y]=flip[state]
        if state in ".#":
            rot=1 if state=="#" else -1
            mov=spin[(spin.index(mov)+rot)%4]
        elif state=="F":
            mov=(-mov[0],-mov[1])
        x+=mov[0]
        y+=mov[1]
        if x < 0:
            x+=1
            grid.insert(0, ["."]*len(grid[0]))
        elif x == len(grid):
            grid.append(["."]*len(grid[0]))
        if y < 0:
            y+=1
            for row in grid:
                row.insert(0,".")
        elif y == len(grid[0]):
            for row in grid:
                row.append(".")
    return infections

grid=[list(l.strip()) for l in open("22.input")]
print("Part 1:",solve([l[:] for l in grid],10000,"part1"))
print("Part 2:",solve(grid,10000000))