day 15 done

README.md

@@ -40,7 +40,7 @@ function writtenIn(day: number): string {
 | 12  |           ✅            |           ✅            |
 | 13  |           ✅            |           ✅            |
 | 14  |           ✅            |           ✅            |
-| 15  |           ❌            |           ❌            |
+| 15  |           ✅            |           ✅            |
 | 16  |           ❌            |           ❌            |
 | 17  |           ❌            |           ❌            |
 | 18  |           ❌            |           ❌            |
@@ -109,5 +109,8 @@ day 13:
 day 14:
 	part 1: 15403588588538
 	part 2: 3260587250457
+day 15:
+	part 1: 421
+	part 2: 436
   ```
 </details>

inputs/day15.txt

@@ -0,0 +1 @@
+20,0,1,11,6,3

run.sh

@@ -12,4 +12,5 @@ dart run src/day09.dart &&
 dotnet script src/day11.cs &&
 swift src/day12.swift &&
 cargo +nightly eval src/day13.rs &&
-go run src/day14.go
+go run src/day14.go &&
+julia src/day15.jl

src/day15.jl

@@ -0,0 +1,34 @@
+get_inputs() = open("./inputs/day15.txt") do f
+	readlines(f)[1] |> l -> split(l, ",") .|> string .|> String |> l -> parse.(Int, l)
+end
+
+
+function run_game(upto)
+	nums = get_inputs()
+
+	prev = pop!(nums)
+
+	memo = Dict((num, i) for (i, num) in enumerate(nums))
+
+	turn = length(nums) + 1
+
+	while turn != upto
+		if haskey(memo, prev)
+			memo[prev], prev = turn, turn - memo[prev]
+		else
+			memo[prev] = turn
+			prev = 0
+		end
+
+		turn += 1
+	end
+
+	return prev
+end
+
+
+
+part1() = run_game(2020)
+part2() = run_game(30000000)
+
+println("day 15:\n\tpart 1: ", part1(), "\n\tpart 2: ", part2())