From 2a35384c761630d4301ef7a4b9c7bd2a4b2b2863 Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Fri, 22 Dec 2017 16:15:32 +0100
Subject: [PATCH] Solve day 22, in Julia.

Only know programming languages left!
---
 2017/README.md          |  6 ++--
 2017/day-22/input.txt   | 25 ++++++++++++++
 2017/day-22/solution.jl | 74 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 101 insertions(+), 4 deletions(-)
 create mode 100644 2017/day-22/input.txt
 create mode 100755 2017/day-22/solution.jl

diff --git a/2017/README.md b/2017/README.md
index c60e3c5..1ac7519 100644
--- a/2017/README.md
+++ b/2017/README.md
@@ -17,6 +17,7 @@ The current plan, in no particular order:
 - [x] Groovy - [Day 16](./day-16/solution.groovy)
 - [x] Haskell - [Day 15](./day-15/solution.hs)
 - [ ] Java
+- [x] Julia - [Day 22](./day-22/solution.jl)
 - [x] Kotlin - [Day 10](./day-10/solution.kt)
 - [x] Lex - [Day 09](./day-09/solution.l)
 - [x] Lua - [Day 18](./day-18/solution.lua)
@@ -25,14 +26,11 @@ The current plan, in no particular order:
 - [ ] Objective C
 - [x] Perl - [Day 05](./day-05/solution.pl)
 - [x] PHP - [Day 19](./day-19/solution.php)
-- [ ] Prolog
 - [ ] Python
 - [x] R - [Day 20](./day-20/solution.r)
 - [x] Ruby - [Day 08](./day-08/solution.rb)
 - [x] Rust - [Day 14](./day-14/solution.rs)
 - [x] Scala - [Day 11](./day-11/solution.scala)
-- [ ] Scheme
-- [ ] SQL
 - [x] Swift - [Day 17](./day-17/solution.swift)
 
-… and then I will need some more. But that will come in time.
+… and then I will be done!
diff --git a/2017/day-22/input.txt b/2017/day-22/input.txt
new file mode 100644
index 0000000..b0b7886
--- /dev/null
+++ b/2017/day-22/input.txt
@@ -0,0 +1,25 @@
+##.###.....##..#.####....
+##...#.#.#..##.#....#.#..
+...#..#.###.#.###.##.####
+..##..###....#.##.#..##.#
+###....#####..###.#..#..#
+.....#.#...#..##..#.##...
+.##.#.###.#.#...##.#.##.#
+......######.###......###
+#.....##.#....#...#......
+....#..###.#.#.####.##.#.
+.#.#.##...###.######.####
+####......#...#...#..#.#.
+###.##.##..##....#..##.#.
+..#.###.##..#...#######..
+...####.#...###..#..###.#
+..#.#.......#.####.#.....
+..##..####.######..##.###
+..#..#..##...#.####....#.
+.#..#.####.#..##..#..##..
+......#####...#.##.#....#
+###..#...#.#...#.#..#.#.#
+.#.###.#....##..######.##
+##.######.....##.#.#.#..#
+..#..##.##..#.#..###.##..
+#.##.##..##.#.###.......#
diff --git a/2017/day-22/solution.jl b/2017/day-22/solution.jl
new file mode 100755
index 0000000..7f6e3ea
--- /dev/null
+++ b/2017/day-22/solution.jl
@@ -0,0 +1,74 @@
+#!/usr/bin/env julia
+worldSize = 0
+
+infected = Set()
+
+for line in eachline(STDIN)
+	for (index, c) in enumerate(line)
+		coord = index - 1 + worldSize * 1im
+		if c == '#'
+			push!(infected, coord)
+		end
+	end
+
+	worldSize += 1
+end
+
+function part1(initial, virusPos)
+	infected = union(Set(), initial)
+	virusDir = -1im
+	infections = 0
+
+	for i = 1:10000
+		if in(virusPos, infected)
+			virusDir *= 1im
+			delete!(infected, virusPos)
+		else
+			push!(infected, virusPos)
+			virusDir *= -1im
+			infections += 1
+		end
+
+		virusPos += virusDir
+	end
+
+	println(infections)
+end
+
+function part2(initial, virusPos)
+	state = Dict()
+	virusDir = -1im
+
+	for node in initial
+		state[node] = 'I'
+	end
+
+	infections = 0
+
+	for i = 1:10000000
+		s = get(state, virusPos, 'C')
+
+		if s == 'C'
+			state[virusPos] = 'W'
+			virusDir *= -1im
+		elseif s == 'W'
+			state[virusPos] = 'I'
+			infections += 1
+		elseif s == 'I'
+			state[virusPos] = 'F'
+			virusDir *= 1im
+		else
+			state[virusPos] = 'C'
+			virusDir *= -1
+		end
+
+		virusPos += virusDir
+	end
+
+	println(infections)
+end
+
+virusPos = (1 + 1im) * trunc(Int, worldSize / 2)
+
+part1(infected, virusPos)
+part2(infected, virusPos)