day10 p2

day10/day10.jl

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+#!/usr/bin/env julia
+
+using Test
+
+mutable struct Instruction
+  cycles :: UInt
+  add    :: Int
+end
+
+function parse_instruction_line(line)
+  parts = split(line, limit=2)
+  if parts[1] == "noop"
+    return Instruction(1, 0)
+  elseif parts[1] == "addx"
+    return Instruction(2, parse(Int, parts[2]))
+  else
+    throw(DomainError("Unknown instruction: " * line))
+  end
+end
+
+function signal_strength_sum(io; end_cycle=220)
+  X :: Int = 1
+  cycle :: Int = 1
+  signal_strength_sum :: Int = 0
+  next_test_cycle = 20
+  for line in eachline(io)
+    if mod(cycle - 20, 40) == 0 && cycle <= end_cycle
+      println(cycle, " ", X)
+      signal_strength_sum += cycle * X
+      next_test_cycle += 40
+    end
+    inst = parse_instruction_line(line)
+    new_cycle = cycle + inst.cycles
+    if new_cycle > next_test_cycle
+      signal_strength_sum += next_test_cycle * X
+      next_test_cycle += 40
+    end
+    cycle = new_cycle
+    X += inst.add
+  end
+  println("last inst cycle ", cycle)
+  signal_strength_sum += X * sum(filter(x -> x >= cycle, 20:40:end_cycle))
+  return signal_strength_sum
+end
+
+function get_crt(io; end_cycle=240)
+  X :: Int = 2 # Note: add 1 to simplify 1-based indexing
+  pending_instruction :: Union{Instruction, Nothing} = nothing
+  screen = fill('.', (Int(ceil(end_cycle / 40)), 40))
+  nrows, ncols = size(screen)
+  for i in 1:nrows
+    for j in 1:ncols
+      if abs(X - j) <= 1
+        screen[i, j] = "#"[1]
+      else 
+        screen[i, j] = '.'
+      end
+
+      if pending_instruction === nothing
+        if eof(io)
+          continue
+        end
+        inst = parse_instruction_line(readline(io))
+        pending_instruction = inst
+      end
+      pending_instruction.cycles -= 1
+      if pending_instruction.cycles == 0
+        X += pending_instruction.add
+        pending_instruction = nothing
+      end
+    end
+  end
+  return join(reduce(*, screen, dims=2, init=""), "\n")
+end
+
+function test()
+  @testset "signal strength sum" verbose=true begin
+    @test signal_strength_sum("example.txt") == 13140
+    @test signal_strength_sum("input.txt") == 13220
+  end
+  @testset "crt test" verbose=true begin
+    open("example.txt") do io
+      @test get_crt(io) == chomp(read("example_crt.txt", String))
+    end
+    open("input.txt") do io
+      @test get_crt(io) == chomp(read("input_crt.txt", String))
+    end
+  end
+end
+
+function main()
+  if size(ARGS, 1) == 0
+    test()
+  else
+    infile = ARGS[1]
+    println("infile = ", infile)
+    println("signal strength sum = ", signal_strength_sum(infile))
+    open(infile, "r") do io
+      println(get_crt(io))
+    end
+  end
+end
+
+main()

day10/example.txt

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+addx 15
+addx -11
+addx 6
+addx -3
+addx 5
+addx -1
+addx -8
+addx 13
+addx 4
+noop
+addx -1
+addx 5
+addx -1
+addx 5
+addx -1
+addx 5
+addx -1
+addx 5
+addx -1
+addx -35
+addx 1
+addx 24
+addx -19
+addx 1
+addx 16
+addx -11
+noop
+noop
+addx 21
+addx -15
+noop
+noop
+addx -3
+addx 9
+addx 1
+addx -3
+addx 8
+addx 1
+addx 5
+noop
+noop
+noop
+noop
+noop
+addx -36
+noop
+addx 1
+addx 7
+noop
+noop
+noop
+addx 2
+addx 6
+noop
+noop
+noop
+noop
+noop
+addx 1
+noop
+noop
+addx 7
+addx 1
+noop
+addx -13
+addx 13
+addx 7
+noop
+addx 1
+addx -33
+noop
+noop
+noop
+addx 2
+noop
+noop
+noop
+addx 8
+noop
+addx -1
+addx 2
+addx 1
+noop
+addx 17
+addx -9
+addx 1
+addx 1
+addx -3
+addx 11
+noop
+noop
+addx 1
+noop
+addx 1
+noop
+noop
+addx -13
+addx -19
+addx 1
+addx 3
+addx 26
+addx -30
+addx 12
+addx -1
+addx 3
+addx 1
+noop
+noop
+noop
+addx -9
+addx 18
+addx 1
+addx 2
+noop
+noop
+addx 9
+noop
+noop
+noop
+addx -1
+addx 2
+addx -37
+addx 1
+addx 3
+noop
+addx 15
+addx -21
+addx 22
+addx -6
+addx 1
+noop
+addx 2
+addx 1
+noop
+addx -10
+noop
+noop
+addx 20
+addx 1
+addx 2
+addx 2
+addx -6
+addx -11
+noop
+noop
+noop

day10/example_crt.txt

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

day10/input.txt

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+noop
+noop
+addx 5
+addx 3
+addx -2
+noop
+addx 5
+addx 4
+noop
+addx 3
+noop
+addx 2
+addx -17
+addx 18
+addx 3
+addx 1
+noop
+addx 5
+noop
+addx 1
+addx 2
+addx 5
+addx -40
+noop
+addx 5
+addx 2
+addx 3
+noop
+addx 2
+addx 3
+addx -2
+addx 2
+addx 2
+noop
+addx 3
+addx 5
+addx 2
+addx 3
+addx -2
+addx 2
+addx -24
+addx 31
+addx 2
+addx -33
+addx -6
+addx 5
+addx 2
+addx 3
+noop
+addx 2
+addx 3
+noop
+addx 2
+addx -1
+addx 6
+noop
+noop
+addx 1
+addx 4
+noop
+noop
+addx -15
+addx 20
+noop
+addx -23
+addx 27
+noop
+addx -35
+addx 1
+noop
+noop
+addx 5
+addx 11
+addx -10
+addx 4
+addx 1
+noop
+addx 2
+addx 2
+noop
+addx 3
+noop
+addx 3
+addx 2
+noop
+addx 3
+addx 2
+addx 11
+addx -4
+addx 2
+addx -38
+addx -1
+addx 2
+noop
+addx 3
+addx 5
+addx 2
+addx -7
+addx 8
+addx 2
+addx 2
+noop
+addx 3
+addx 5
+addx 2
+addx -25
+addx 26
+addx 2
+addx 8
+addx -1
+addx 2
+addx -2
+addx -37
+addx 5
+addx 3
+addx -1
+addx 5
+noop
+addx 22
+addx -21
+addx 2
+addx 5
+addx 2
+addx 13
+addx -12
+addx 4
+noop
+noop
+addx 5
+addx 1
+noop
+noop
+addx 2
+noop
+addx 3
+noop
+noop

day10/input_crt.txt

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