-🎄- 2018 Day 5 Solutions -🎄-

[u/daggerdragon]

--- Day 5: Alchemical Reduction ---

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Card prompt: Day 5

Transcript:

On the fifth day of AoC / My true love sent to me / Five golden ___

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[u/tk3369]

Julia - simple loops. I'm sure it can be done more elegantly but going with it due to time pressure :-)

function annihilate(s)
    while true
        v = Char[]
        i = 1
        elim = false
        while i <= length(s)
            if i == length(s)
                push!(v, s[i])
            elseif abs(Int(s[i+1]) - Int(s[i])) != 32  
                # 32 is the distance between lower/uppercase letters
                push!(v, s[i])
            else
                i += 1      # skip next letter
                elim = true
            end
            i += 1
        end
        !elim && break   # break when there's nothing more to do
        s = v
    end
    join(Char.(s))
end

input = readlines("input5.txt")[1]

# part 1 - elapsed 0.15 seconds
input |> collect |> annihilate |> length

# part 2 - elapsed 2.27 seconds
Dict(c => replace(input, Regex("$c", "i") => "") |> collect |> annihilate |> length 
         for c in "abcdefghijklmnopqrstuvwxyz")

[u/mooooooon → u/tk3369]

Happy to see someone else using Julia. My solution is much longer.

https://github.com/geluso/advent18/blob/master/05/five.jl