Add solution for day 13

README.md

@@ -15,4 +15,5 @@
 | 09 | 414.915 ms | 55001| 7.39 MiB |
 | 10 | 360.287 μs | 932| 154.28 KiB |
 | 11 | 12.206 ms | 85| 817.98 KiB |
-| 12 | 3.904 ms | 4620| 2.33 MiB |
+| 12 | 3.904 ms | 4620| 2.33 MiB |
+| 13 | 127.304 μs | 4162| 185.08 KiB |

solutions/2024/src/AdventOfCode24.jl

@@ -8,7 +8,7 @@ module AdventOfCode24
     readInput(day::Int) = AdventOfCode.readInput(day, year)
     export readInput
 
-    solvedDays = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
+    solvedDays = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]
 
     # Include the source files:
     for day in solvedDays

solutions/2024/src/day13.jl

@@ -0,0 +1,47 @@
+module Day13
+    using ..AdventOfCode24
+
+    """
+        day13()
+
+    Solves the two puzzles of day 13. 
+    """
+
+    function day13(input::String = readInput(13))
+        r = r"""Button A: X\+(\d+), Y\+(\d+)
+            Button B: X\+(\d+), Y\+(\d+)
+            Prize: X=(\d+), Y=(\d+)"""
+
+        s0 = 0
+        s1 = 0
+
+        for m in eachmatch(r, input)
+
+            a11, a21, a12, a22, b1, b2 =  parse.(Int, m.captures)
+
+            s0 += solve_matrix(a11, a21, a12, a22, b1, b2)
+
+            b1 += 10000000000000
+            b2 += 10000000000000
+            s1 += solve_matrix(a11, a21, a12, a22, b1, b2)
+        end
+
+        return [s0, s1]
+    end
+
+
+
+    function solve_matrix(a11::Int, a21::Int, a12::Int, a22::Int, b1::Int, b2::Int)
+        det = a11 * a22 - a12 * a21
+
+        c1, r1 = divrem(a22 * b1 - a12 * b2, det)
+        c2, r2 = divrem(a11 * b2 - a21 * b1, det)
+
+        (r1 != 0 || r2 != 0) && return 0
+
+        return 3 * Int(c1) + Int(c2)
+    end
+
+
+end 
+

solutions/2024/test/runtests.jl

@@ -46,3 +46,7 @@ end
 @testset "Day 12" begin
     @test AdventOfCode24.Day12.day12() == [1352976, 808796]
 end
+
+@testset "Day 13" begin
+    @test AdventOfCode24.Day13.day13() == [32067, 92871736253789]
+end