[Day 12] Add solution

Project.toml

@@ -5,6 +5,7 @@ version = "0.1.0"
 
 [deps]
 BenchmarkTools = "6e4b80f9-dd63-53aa-95a3-0cdb28fa8baf"
+Memoize = "c03570c3-d221-55d1-a50c-7939bbd78826"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 
 [compat]

README.md

@@ -21,7 +21,7 @@ This Julia package contains my solutions for [Advent of Code 2023](https://adven
 | 9 | [:white_check_mark:](https://adventofcode.com/2023/day/9) | 1.408 ms | 1.72 MiB | [:white_check_mark:](https://github.com/goggle/AdventOfCode2023.jl/blob/master/src/day09.jl) |
 | 10 | [:white_check_mark:](https://adventofcode.com/2023/day/10) | 43.997 ms | 8.82 MiB | [:white_check_mark:](https://github.com/goggle/AdventOfCode2023.jl/blob/master/src/day10.jl) |
 | 11 | [:white_check_mark:](https://adventofcode.com/2023/day/11) | 4.728 ms | 1.71 MiB | [:white_check_mark:](https://github.com/goggle/AdventOfCode2023.jl/blob/master/src/day11.jl) |
-<!-- | 12 | [:white_check_mark:](https://adventofcode.com/2023/day/12) |  |  | [:white_check_mark:](https://github.com/goggle/AdventOfCode2023.jl/blob/master/src/day12.jl) | -->
+| 12 | [:white_check_mark:](https://adventofcode.com/2023/day/12) | 9.320 ms | 2.64 MiB | [:white_check_mark:](https://github.com/goggle/AdventOfCode2023.jl/blob/master/src/day12.jl) |
 <!-- | 13 | [:white_check_mark:](https://adventofcode.com/2023/day/13) |  |  | [:white_check_mark:](https://github.com/goggle/AdventOfCode2023.jl/blob/master/src/day13.jl) | -->
 <!-- | 14 | [:white_check_mark:](https://adventofcode.com/2023/day/14) |  |  | [:white_check_mark:](https://github.com/goggle/AdventOfCode2023.jl/blob/master/src/day14.jl) | -->
 <!-- | 15 | [:white_check_mark:](https://adventofcode.com/2023/day/15) |  |  | [:white_check_mark:](https://github.com/goggle/AdventOfCode2023.jl/blob/master/src/day15.jl) | -->

src/AdventOfCode2023.jl

@@ -3,7 +3,7 @@ module AdventOfCode2023
 using BenchmarkTools
 using Printf
 
-solvedDays = 1:11
+solvedDays = 1:12
 # Include the source files:
 for day in solvedDays
     ds = @sprintf("%02d", day)

src/day12.jl

@@ -0,0 +1,49 @@
+module Day12
+
+using AdventOfCode2023
+using Memoize
+
+
+function day12(input::String = readInput(joinpath(@__DIR__, "..", "data", "day12.txt")))
+    patterngroups = parse_input(input)
+    p1 = sum(count_combinations(p, g) for (p, g) ∈ patterngroups)
+    return [p1, part2(patterngroups)]
+end
+
+function parse_input(input::AbstractString)
+    patterngroups = []
+    for (pattern, instructions) ∈ split.(eachsplit(rstrip(input), "\n"), " ")
+        numbers = Tuple(parse.(Int, split(instructions, ",")))
+        push!(patterngroups, (pattern, numbers))
+    end
+    return patterngroups
+end
+
+@memoize function count_combinations(pattern::AbstractString, groups::Tuple)
+    count = 0
+    if isempty(groups)
+        '#' ∈ pattern && return 0
+        return 1
+    end
+    length(pattern) < sum(groups) + length(groups) - 1 && return 0
+    if '.' ∉ pattern[begin:groups[begin]]
+        if length(pattern) == groups[begin] || pattern[groups[begin]+1] != '#'
+            count += count_combinations(pattern[groups[begin] + 2:end], groups[begin+1:end])
+        end
+    end
+    if pattern[begin] != '#'
+        count += count_combinations(pattern[begin + 1:end], groups)
+    end
+    return count
+end
+
+function part2(patterngroups)
+    s = Int64(0)
+    for (pattern, groups) ∈ patterngroups
+        pattern = pattern * "?" * pattern * "?" * pattern * "?" * pattern * "?" * pattern
+        s += count_combinations(pattern, Tuple(repeat(collect(groups), 5)))
+    end
+    return s
+end
+
+end # module

test/runtests.jl

@@ -124,4 +124,15 @@ end
              "#...#.....\n"
     @test AdventOfCode2023.Day11.day11(sample) == [374, 82000210]
     @test AdventOfCode2023.Day11.day11() == [10490062, 382979724122]
+end
+
+@testset "Day 12" begin
+    sample = "???.### 1,1,3\n" *
+             ".??..??...?##. 1,1,3\n" *
+             "?#?#?#?#?#?#?#? 1,3,1,6\n" *
+             "????.#...#... 4,1,1\n" *
+             "????.######..#####. 1,6,5\n" *
+             "?###???????? 3,2,1\n"
+    AdventOfCode2023.Day12.day12(sample) == [21, 525152]
+    AdventOfCode2023.Day12.day12() == [7939, 850504257483930]
 end