Solve day 22, in Julia.

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2017/day-22/input.txt

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+##.###.....##..#.####....
+##...#.#.#..##.#....#.#..
+...#..#.###.#.###.##.####
+..##..###....#.##.#..##.#
+###....#####..###.#..#..#
+.....#.#...#..##..#.##...
+.##.#.###.#.#...##.#.##.#
+......######.###......###
+#.....##.#....#...#......
+....#..###.#.#.####.##.#.
+.#.#.##...###.######.####
+####......#...#...#..#.#.
+###.##.##..##....#..##.#.
+..#.###.##..#...#######..
+...####.#...###..#..###.#
+..#.#.......#.####.#.....
+..##..####.######..##.###
+..#..#..##...#.####....#.
+.#..#.####.#..##..#..##..
+......#####...#.##.#....#
+###..#...#.#...#.#..#.#.#
+.#.###.#....##..######.##
+##.######.....##.#.#.#..#
+..#..##.##..#.#..###.##..
+#.##.##..##.#.###.......#

2017/day-22/solution.jl

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+#!/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)