Day 7: Bridge Repair

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FAQ

  • Karmmah@lemmy.world
    1·
    3 days ago

    Julia

    Took quite some time to debug but in the end I think it’s a nice solution using base 2 and 3 numbers counting up to check all operator combinations.

    Code 
    function readInput(inputFile::String)::Vector{Vector{Int}}
	f = open(inputFile,"r")
	lines::Vector{String} = readlines(f)
	close(f)
	equations::Vector{Vector{Int}} = []
	function getValues(line::String)
		return map(sp->parse(Int,sp),(sp=split(line," ");sp[1]=sp[1][1:end-1];sp))
	end
	map(l->push!(equations,getValues(l)),lines)
	return equations
end

function checkEq(eq::Vector{Int},withConCat::Bool)::Bool
	function calcEq(eq::Vector{Int},operators::Vector{Int},withConCat::Bool)::Int
		res::Int = eq[2]
		for (i,op) in enumerate(operators)
			if op == 0 #+
				res += eq[i+2]
			elseif op ==1 #*
				res *= eq[i+2]
			else #op==2 ||
				res = parse(Int,string(res)*string(eq[i+2]))
			end
		end
		return res
	end
	opInt::Int = 0
	operators = Vector{Int}(undef,length(eq)-2)
	while opInt < (withConCat ? 3^(length(eq)-2) : 2^(length(eq)-2))
		withConCat==true ? operators=digits(opInt,base=3,pad=length(eq)-2) : operators=digits(opInt,base=2,pad=length(eq)-2)
		#calcEq(eq,operators,withConCat)==eq[1] ? (return true) : opInt -= 1
		calcEq(eq,operators,withConCat)==eq[1] ? (return true) : opInt += 1
	end
	return false
end

function calcTotCalRes(equations::Vector{Vector{Int}},withConCat::Bool)::Int
	totCalRes::Int = 0
	for e in equations
		checkEq(e,withConCat) ? totCalRes+=e[1] : nothing
	end
	return totCalRes
end

@info "Part 1"
println("result: $(calcTotCalRes(readInput("day07Input"),false))")
@info "Part 2"
println("result: $(calcTotCalRes(readInput("day07Input"),true))")