this post was submitted on 10 Dec 2024
15 points (89.5% liked)

Advent Of Code

985 readers
28 users here now

An unofficial home for the advent of code community on programming.dev!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

AoC 2024

Solution Threads

M T W T F S S
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25

Rules/Guidelines

Relevant Communities

Relevant Links

Credits

Icon base by Lorc under CC BY 3.0 with modifications to add a gradient

console.log('Hello World')

founded 1 year ago
MODERATORS
[email protected]
[email protected]
[email protected]
15
๐Ÿฎ - 2024 DAY 10 SOLUTIONS - ๐Ÿฎ (programming.dev)
submitted 2 weeks ago by [email protected] to c/[email protected]
32 comments fedilink hide all child comments
 

Day 10: Hoof It

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

you are viewing a single comment's thread
view the rest of the comments
[โ€“] [email protected] 2 points 2 weeks ago* (last edited 2 weeks ago)

Julia

Quite happy that today went a lot smoother than yesterday even though I am not really familiar with recursion. Normally I never use recursion but I felt like today could be solved by it (or using trees, but I'm even less familiar with them). Surprisingly my solution actually worked and for part 2 only small modifications were needed to count peaks reached by each trail.

Code

function readInput(inputFile::String)
	f = open(inputFile,"r")
	lines::Vector{String} = readlines(f)
	close(f)
	topoMap = Matrix{Int}(undef,length(lines),length(lines[1]))
	for (i,l) in enumerate(lines)
		topoMap[i,:] = map(x->parse(Int,x),collect(l))
	end
	return topoMap
end

function getTrailheads(topoMap::Matrix{Int})
	trailheads::Vector{Vector{Int}} = []
	for (i,r) in enumerate(eachrow(topoMap))
		for (j,c) in enumerate(r)
			c==0 ? push!(trailheads,[i,j]) : nothing
		end
	end
	return trailheads
end

function getReachablePeaks(topoMap::Matrix{Int},trailheads::Vector{Vector{Int}})
	reachablePeaks = Dict{Int,Vector{Vector{Int}}}()
	function getPossibleMoves(topoMap::Matrix{Int},pos::Vector{Int})
		possibleMoves::Vector{Vector{Int}} = []
		pos[1]-1 in 1:size(topoMap)[1] && topoMap[pos[1]-1,pos[2]]==topoMap[pos[1],pos[2]]+1 ? push!(possibleMoves,[pos[1]-1,pos[2]]) : nothing #up?
		pos[1]+1 in 1:size(topoMap)[1] && topoMap[pos[1]+1,pos[2]]==topoMap[pos[1],pos[2]]+1 ? push!(possibleMoves,[pos[1]+1,pos[2]]) : nothing #down?
		pos[2]-1 in 1:size(topoMap)[2] && topoMap[pos[1],pos[2]-1]==topoMap[pos[1],pos[2]]+1 ? push!(possibleMoves,[pos[1],pos[2]-1]) : nothing #left?
		pos[2]+1 in 1:size(topoMap)[2] && topoMap[pos[1],pos[2]+1]==topoMap[pos[1],pos[2]]+1 ? push!(possibleMoves,[pos[1],pos[2]+1]) : nothing #right?
		return possibleMoves
	end
	function walkPossMoves(topoMap::Matrix{Int},pos::Vector{Int},reachedPeaks::Matrix{Bool},trailId::Int)
		possMoves::Vector{Vector{Int}} = getPossibleMoves(topoMap,pos)
		for m in possMoves
			if topoMap[m[1],m[2]]==9
				reachedPeaks[m[1],m[2]]=1
				trailId += 1
				continue
			end
			reachedPeaks,trailId = walkPossMoves(topoMap,m,reachedPeaks,trailId)
		end
		return reachedPeaks, trailId
	end
	peaksScore::Int = 0; trailsScore::Int = 0
	trailId::Int = 0
	for (i,t) in enumerate(trailheads)
		if !haskey(reachablePeaks,i); reachablePeaks[i]=[]; end
		reachedPeaks::Matrix{Bool} = zeros(size(topoMap))
		trailId = 0
		reachedPeaks,trailId = walkPossMoves(topoMap,t,reachedPeaks,trailId)
		trailPeaksScore = sum(reachedPeaks)
		peaksScore += trailPeaksScore
		trailsScore += trailId
	end
	return peaksScore,trailsScore
end #getReachablePeaks

topoMap::Matrix{Int} = readInput("input/day10Input")
trailheads::Vector{Vector{Int}} = getTrailheads(topoMap)
@info "Part 1"
reachablePeaks = getReachablePeaks(topoMap,trailheads)[1]
println("reachable peaks: ",reachablePeaks)
@info "Part 2"
trailsScore::Int = getReachablePeaks(topoMap,trailheads)[2]
println("trails score: $trailsScore")