[Day 23] Add solution

Author: goggle

README.md

@@ -31,8 +31,8 @@ This Julia package contains my solutions for [Advent of Code 2024](https://adven
 | 19 | [:white_check_mark:](https://adventofcode.com/2024/day/19) | 59.678 ms | 3.41 MiB| [:white_check_mark:](https://github.com/goggle/AdventOfCode2024.jl/blob/main/src/day19.jl) |
 | 20 | [:white_check_mark:](https://adventofcode.com/2024/day/20) | 227.453 ms | 224.97 MiB| [:white_check_mark:](https://github.com/goggle/AdventOfCode2024.jl/blob/main/src/day20.jl) |
 | 22 | [:white_check_mark:](https://adventofcode.com/2024/day/22) | 241.724 ms | 78.80 MiB | [:white_check_mark:](https://github.com/goggle/AdventOfCode2024.jl/blob/main/src/day22.jl) |
+| 23 | [:white_check_mark:](https://adventofcode.com/2024/day/23) | 4.197 ms | 3.82 MiB | [:white_check_mark:](https://github.com/goggle/AdventOfCode2024.jl/blob/main/src/day23.jl) |
 <!-- | 21 | [:white_check_mark:](https://adventofcode.com/2024/day/21) | 9.675 ms | 7.19 MiB | [:white_check_mark:](https://github.com/goggle/AdventOfCode2024.jl/blob/main/src/day21.jl) | -->
-<!-- | 23 | [:white_check_mark:](https://adventofcode.com/2024/day/23) | 2.979 s | 9.69 MiB | [:white_check_mark:](https://github.com/goggle/AdventOfCode2024.jl/blob/main/src/day23.jl) | -->
 <!-- | 24 | [:white_check_mark:](https://adventofcode.com/2024/day/24) | 43.214 ms | 49.77 MiB | [:white_check_mark:](https://github.com/goggle/AdventOfCode2024.jl/blob/main/src/day24.jl) | -->
 <!-- | 25 | [:white_check_mark:](https://adventofcode.com/2024/day/25) | 69.476 ms | 62.03 MiB | [:white_check_mark:](https://github.com/goggle/AdventOfCode2024.jl/blob/main/src/day25.jl) | -->
 

data

@@ -3,7 +3,7 @@ module AdventOfCode2024
 using BenchmarkTools
 using Printf
 
-solvedDays = 1:22
+solvedDays = 1:23
 # Include the source files:
 for day in solvedDays
     ds = @sprintf("%02d", day)

src/AdventOfCode2024.jl

@@ -0,0 +1,70 @@
+module Day23
+
+using AdventOfCode2024
+
+
+function day23(input::String = readInput(joinpath(@__DIR__, "..", "data", "day23.txt")))
+    connections = split.(split(rstrip(input), '\n'), '-')
+    network = zeros(Bool, _computer_to_index("zz"), _computer_to_index("zz"))
+    for (a, b) ∈ connections
+        ind_a = _computer_to_index(a)
+        ind_b = _computer_to_index(b)
+        network[ind_a, ind_b] = true
+        network[ind_b, ind_a] = true
+    end
+    triangles = find_triangles(network)
+    p1 = count(any(t[1] == 't' for t ∈ tri) for tri ∈ triangles)
+    return [p1, join(_index_to_computer.(find_largest_network(network)) |> sort, ',')]
+end
+
+function parse_input(input)
+    split.(split(rstrip(input), '\n'), '-')
+end
+
+function find_triangles(network::Matrix{Bool})
+    triangles = Tuple{String,String,String}[]
+    for i ∈ axes(network, 1)
+        for j ∈ i + 1:size(network,2)
+            if network[i, j]
+                for k ∈ j + 1:size(network,2)
+                    if network[j, k] && network[k, i]
+                        push!(triangles, (_index_to_computer(i), _index_to_computer(j), _index_to_computer(k)))
+                    end
+                end
+            end
+        end
+    end
+    return triangles
+end
+
+function find_largest_network(network::Matrix{Bool})
+    visited = zeros(Bool, size(network,1))
+    largest_component = Int[]
+
+    for vertex ∈ 1:size(network, 1)
+        if !visited[vertex]
+            current_component = Int[]
+            component = dfs!(current_component, visited, network, vertex)
+            if length(component) > length(largest_component)
+                largest_component = copy(component)
+            end
+        end
+    end
+    return largest_component
+end
+
+function dfs!(component::Vector{Int}, visited::Vector{Bool}, network::Matrix{Bool}, vertex::Int)
+    visited[vertex] = true
+    push!(component, vertex)
+    for neighbour ∈ 1:size(network, 1)
+        if !visited[neighbour] && network[vertex, neighbour] && all(network[neighbour, comp] for comp ∈ component)
+            dfs!(component, visited, network, neighbour)
+        end
+    end
+    return component
+end
+
+_computer_to_index(c::AbstractString) = (Int(c[1] - Int('a'))) * 26 + (Int(c[2]) - Int('a'))
+_index_to_computer(index::Int) = Char(Int('a') + index ÷ 26) * Char(Int('a') + index % 26)
+
+end # module

src/day23.jl

@@ -342,4 +342,41 @@ end
     @test AdventOfCode2024.Day22.day22(sample2) == [37990510, 23]
 
     @test AdventOfCode2024.Day22.day22() == [13185239446, 1501]
+end
+
+@testset "Day 23" begin
+    sample = "kh-tc\n" *
+             "qp-kh\n" *
+             "de-cg\n" *
+             "ka-co\n" *
+             "yn-aq\n" *
+             "qp-ub\n" *
+             "cg-tb\n" *
+             "vc-aq\n" *
+             "tb-ka\n" *
+             "wh-tc\n" *
+             "yn-cg\n" *
+             "kh-ub\n" *
+             "ta-co\n" *
+             "de-co\n" *
+             "tc-td\n" *
+             "tb-wq\n" *
+             "wh-td\n" *
+             "ta-ka\n" *
+             "td-qp\n" *
+             "aq-cg\n" *
+             "wq-ub\n" *
+             "ub-vc\n" *
+             "de-ta\n" *
+             "wq-aq\n" *
+             "wq-vc\n" *
+             "wh-yn\n" *
+             "ka-de\n" *
+             "kh-ta\n" *
+             "co-tc\n" *
+             "wh-qp\n" *
+             "tb-vc\n" *
+             "td-yn\n"
+    @test AdventOfCode2024.Day23.day23(sample) == [7, "co,de,ka,ta"]
+    @test AdventOfCode2024.Day23.day23() == [1368, "dd,ig,il,im,kb,kr,pe,ti,tv,vr,we,xu,zi"]
 end