Day 8 Parts 1 and 2
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@ -2,7 +2,7 @@
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My (attempted) solutions to [Advent of Code 2020](https://adventofcode.com/2020) in Elixir.
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<img width="981" alt="image" src="https://user-images.githubusercontent.com/498229/101322836-063a9e00-38ab-11eb-90bc-3450075df1e9.png">
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<img width="975" alt="image" src="https://user-images.githubusercontent.com/498229/101474250-39a22900-398e-11eb-9716-42b0d65171e4.png">
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## Strategy
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@ -0,0 +1,41 @@
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Day 8 Notes
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+--------+
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| Part 1 |
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+--------+
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$ elixir day8part1.exs
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1528
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Thoughts:
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Loop detection. Have a feeling I'm supposed to detect patterns, but I decided to just store the
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index of every instruction executed, and stop as soon as we visit a previously-seen instruction.
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A little bit annoyed about using an if/else statement for the terminating condition. I would have
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preferred to use pattern matching, but I'm not sure that's possible with a MapSet.
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+--------+
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| Part 2 |
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+--------+
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$ elixir day8part2.exs
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640
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Thoughts:
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Adapt the algorithm from part 1 to also detect when the last command has been executed (when the
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0-based index is the same as the number of commands). Renamed run_until_loop → try_boot
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Iterate through all the commands, toggling each one and try executing the program to see if it completes.
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Could technically skip the acc commands, but decided to just leave them in to keep the code simpler.
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+------------------+
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| Overall Thoughts |
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+------------------+
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I was a little concerned that this would be slow, due to it being O(n²) - togging each instruction in turn,
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then executing the full instruction set, however there are only ~600 instructions, so it completes
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pretty quickly.
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@ -0,0 +1,34 @@
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defmodule Day8Part1 do
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def run do
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File.read!("input")
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|> input_to_instrs()
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|> run_until_loop()
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|> IO.puts()
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end
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def input_to_instrs(input) do
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input
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|> String.split("\n", trim: true)
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|> Enum.map(&Regex.run(~r/\A(\w{3}) ([+\-]\d+)\z/, &1, capture: :all_but_first))
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|> Enum.with_index()
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|> Map.new(fn {[op, arg], idx} -> {idx, {op, String.to_integer(arg)}} end)
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end
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def run_until_loop(instrs), do: run_until_loop(instrs, 0, 0, MapSet.new())
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def run_until_loop(instrs, idx, acc, seen) do
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if MapSet.member?(seen, idx) do
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acc
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else
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seen = MapSet.put(seen, idx)
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{idx, acc} = execute(instrs[idx], idx, acc)
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run_until_loop(instrs, idx, acc, seen)
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end
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end
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def execute({"nop", _arg}, idx, acc), do: {idx + 1, acc}
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def execute({"jmp", arg}, idx, acc), do: {idx + arg, acc}
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def execute({"acc", arg}, idx, acc), do: {idx + 1, acc + arg}
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end
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Day8Part1.run()
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@ -0,0 +1,53 @@
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defmodule Day8Part2 do
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def run do
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File.read!("input")
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|> input_to_instrs()
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|> find_corrupted()
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|> IO.puts()
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end
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def input_to_instrs(input) do
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input
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|> String.split("\n", trim: true)
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|> Enum.map(&Regex.run(~r/\A(\w{3}) ([+\-]\d+)\z/, &1, capture: :all_but_first))
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|> Enum.with_index()
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|> Map.new(fn {[op, arg], idx} -> {idx, {op, String.to_integer(arg)}} end)
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end
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def find_corrupted(instrs), do: find_corrupted(Map.to_list(instrs), instrs, :loop)
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def find_corrupted(_rest, _instrs, {:terminated, acc}), do: acc
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def find_corrupted([{idx, {op, arg}} | rest], instrs, :loop) do
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result =
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instrs
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|> Map.put(idx, toggle_op(op, arg))
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|> try_boot()
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find_corrupted(rest, instrs, result)
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end
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def toggle_op("acc", arg), do: {"acc", arg}
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def toggle_op("nop", arg), do: {"jmp", arg}
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def toggle_op("jmp", arg), do: {"nop", arg}
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def try_boot(instrs), do: try_boot(instrs, 0, 0, MapSet.new())
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def try_boot(instrs, idx, acc, _seen) when idx == map_size(instrs), do: {:terminated, acc}
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def try_boot(instrs, idx, acc, seen) do
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if MapSet.member?(seen, idx) do
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:loop
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else
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seen = MapSet.put(seen, idx)
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{idx, acc} = execute(instrs[idx], idx, acc)
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try_boot(instrs, idx, acc, seen)
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end
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end
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def execute({"nop", _arg}, idx, acc), do: {idx + 1, acc}
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def execute({"jmp", arg}, idx, acc), do: {idx + arg, acc}
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def execute({"acc", arg}, idx, acc), do: {idx + 1, acc + arg}
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end
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Day8Part2.run()
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@ -0,0 +1,608 @@
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jmp +232
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acc +21
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nop +120
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jmp +239
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acc +18
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acc +41
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jmp +72
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acc +47
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jmp +314
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jmp +1
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acc +47
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nop +175
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acc +33
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jmp +115
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nop -5
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acc +37
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acc +25
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acc +18
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jmp +304
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acc +0
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acc +16
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jmp +77
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acc +9
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acc -3
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jmp +93
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acc +16
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acc -15
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jmp +110
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jmp +76
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acc +36
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acc +11
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acc -3
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jmp +258
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jmp +241
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acc +42
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jmp +514
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nop +103
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acc +36
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acc -18
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jmp +47
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acc +5
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acc +37
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jmp +480
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acc -16
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jmp +1
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nop +498
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jmp +1
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jmp +12
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acc +0
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acc +35
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jmp +437
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jmp +326
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acc -15
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acc -7
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nop -2
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jmp +548
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jmp -4
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jmp +395
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jmp +258
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acc +37
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acc +17
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acc -18
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jmp +345
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acc -18
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acc +37
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acc +36
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jmp +217
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acc -4
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acc +39
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jmp -35
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jmp +252
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jmp +1
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nop +91
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jmp +402
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nop -40
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jmp +371
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jmp -72
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jmp +9
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acc +41
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jmp +95
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nop +252
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nop +30
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jmp +240
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nop +266
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jmp +462
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jmp +137
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acc -14
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jmp +203
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jmp +1
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acc +45
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acc -14
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acc -6
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jmp -9
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acc -15
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acc +6
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nop +298
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jmp -56
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jmp +14
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acc +32
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jmp +40
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acc +17
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nop +62
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acc +14
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jmp +119
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acc +49
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jmp -29
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acc +27
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acc -12
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acc +14
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acc +19
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jmp +253
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acc +19
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jmp +345
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acc -17
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acc +39
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jmp +1
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jmp +133
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jmp +268
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acc -14
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acc -16
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acc +45
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jmp +373
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jmp +116
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jmp +245
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acc -19
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acc +32
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jmp -22
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jmp +105
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acc -9
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acc +27
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acc +16
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nop +397
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jmp +110
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acc +13
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acc -10
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acc +10
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jmp -69
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jmp +29
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jmp +94
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acc +38
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acc +49
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acc +40
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jmp +261
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acc +43
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acc -13
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jmp +214
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acc -10
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nop -80
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acc +15
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jmp +228
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acc +0
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jmp +275
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jmp -69
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acc +46
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acc +4
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acc +24
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acc +6
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jmp +279
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acc -9
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nop +281
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jmp +286
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acc -4
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jmp +306
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jmp +342
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acc -14
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jmp +357
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acc -10
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nop -9
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acc +10
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acc +40
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jmp +427
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acc +0
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acc +32
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jmp +405
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acc +45
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acc +34
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nop +281
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acc +34
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jmp +394
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acc +41
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acc +20
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jmp -98
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jmp -60
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acc -3
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acc +17
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jmp +19
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acc +6
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nop +168
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acc +35
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jmp -141
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nop -62
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acc +8
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acc +16
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jmp +117
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acc +34
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acc -8
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acc +35
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acc -15
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jmp +85
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acc +2
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acc -9
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acc -4
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acc +49
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jmp +394
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nop -145
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acc +47
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jmp +16
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acc +10
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acc +0
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jmp +87
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nop -88
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acc -9
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acc -16
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acc +45
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jmp +374
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acc +28
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acc +38
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jmp -139
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acc -13
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acc +13
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jmp +143
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jmp -135
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jmp -4
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jmp -130
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acc +5
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nop -196
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jmp +48
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acc -10
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jmp +149
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acc -14
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jmp +210
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jmp +325
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acc +45
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acc +11
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acc -15
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jmp +97
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nop +107
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jmp -98
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acc -7
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acc -18
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jmp -181
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jmp +122
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acc -15
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jmp -49
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jmp +1
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acc +36
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acc -10
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jmp +1
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jmp +62
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acc +39
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jmp +105
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acc +19
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nop +253
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acc -11
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acc -9
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jmp +77
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acc +50
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acc +3
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acc -18
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acc +17
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jmp +56
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nop -209
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nop +272
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acc -13
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jmp +270
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nop +229
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acc +12
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jmp +1
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jmp -44
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acc -13
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jmp +1
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nop +275
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acc +45
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jmp -254
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acc -2
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acc -2
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nop -148
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jmp -91
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acc +2
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nop -30
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acc -8
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acc +0
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jmp -96
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nop +1
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jmp -74
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acc -19
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||||
acc +10
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acc +26
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acc +30
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jmp -280
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acc +46
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acc -2
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acc -8
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jmp +277
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acc -9
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jmp +205
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acc -13
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acc +10
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jmp +1
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jmp +219
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acc +38
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acc +24
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acc +11
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jmp -129
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jmp -86
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jmp +1
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acc +0
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jmp +1
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acc +46
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jmp -135
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nop +218
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acc -14
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acc +0
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jmp +55
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acc +24
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jmp +213
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||||
acc +19
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||||
acc +16
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jmp -266
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||||
acc +24
|
||||
acc +15
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||||
jmp +158
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||||
acc +3
|
||||
jmp -94
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||||
acc +16
|
||||
acc +24
|
||||
acc +42
|
||||
jmp +201
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||||
jmp -32
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||||
acc +34
|
||||
nop -321
|
||||
jmp +212
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||||
acc +12
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||||
acc +41
|
||||
jmp -212
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||||
acc +32
|
||||
jmp +236
|
||||
acc +45
|
||||
nop +253
|
||||
jmp +129
|
||||
nop -3
|
||||
acc +38
|
||||
jmp +35
|
||||
acc -15
|
||||
acc +21
|
||||
acc -7
|
||||
acc -6
|
||||
jmp +46
|
||||
jmp -5
|
||||
acc +5
|
||||
acc +4
|
||||
acc +42
|
||||
jmp +142
|
||||
acc +36
|
||||
jmp -180
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||||
acc +23
|
||||
jmp -46
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||||
acc +12
|
||||
jmp +5
|
||||
jmp +201
|
||||
acc +36
|
||||
acc -14
|
||||
jmp -30
|
||||
jmp -338
|
||||
acc +12
|
||||
acc +34
|
||||
acc +2
|
||||
jmp -310
|
||||
acc -15
|
||||
jmp -104
|
||||
jmp -148
|
||||
jmp +108
|
||||
acc +37
|
||||
acc -6
|
||||
acc +0
|
||||
acc +13
|
||||
jmp -324
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||||
acc +49
|
||||
acc +37
|
||||
acc +37
|
||||
jmp +131
|
||||
acc +2
|
||||
acc +30
|
||||
acc +12
|
||||
jmp -238
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||||
acc -12
|
||||
acc +4
|
||||
jmp -155
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||||
acc +45
|
||||
acc -10
|
||||
nop -168
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||||
nop +114
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||||
jmp +113
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||||
acc +15
|
||||
acc +41
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||||
acc +6
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||||
acc +34
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||||
jmp +25
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||||
acc +46
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||||
acc +28
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||||
acc +44
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acc -3
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||||
jmp -70
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acc +2
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||||
acc +37
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||||
jmp -101
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||||
jmp +51
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||||
acc +45
|
||||
nop -399
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||||
nop -60
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||||
jmp -391
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||||
acc +41
|
||||
jmp -57
|
||||
jmp -54
|
||||
acc +46
|
||||
jmp +90
|
||||
acc +6
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||||
jmp +83
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||||
acc +37
|
||||
jmp +1
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||||
acc -6
|
||||
jmp -189
|
||||
acc +0
|
||||
jmp -241
|
||||
acc +35
|
||||
jmp -396
|
||||
acc +35
|
||||
acc +42
|
||||
acc +37
|
||||
acc +20
|
||||
jmp -81
|
||||
nop +74
|
||||
acc +41
|
||||
acc +23
|
||||
jmp +1
|
||||
jmp -349
|
||||
jmp -232
|
||||
acc +37
|
||||
acc +24
|
||||
jmp +121
|
||||
jmp -144
|
||||
acc +35
|
||||
acc +39
|
||||
acc -12
|
||||
acc +14
|
||||
jmp -113
|
||||
acc +2
|
||||
acc +29
|
||||
acc -6
|
||||
acc +0
|
||||
jmp -326
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||||
jmp -426
|
||||
acc +18
|
||||
acc +39
|
||||
acc +22
|
||||
jmp +79
|
||||
jmp +23
|
||||
acc -17
|
||||
nop +42
|
||||
acc -8
|
||||
jmp -47
|
||||
acc -12
|
||||
jmp -276
|
||||
jmp -126
|
||||
acc +20
|
||||
acc +3
|
||||
acc +41
|
||||
jmp -31
|
||||
acc -1
|
||||
jmp +1
|
||||
jmp -241
|
||||
acc +9
|
||||
acc +12
|
||||
acc +0
|
||||
jmp +26
|
||||
acc +30
|
||||
nop +46
|
||||
jmp -134
|
||||
jmp -361
|
||||
acc +50
|
||||
nop -1
|
||||
nop -225
|
||||
jmp -226
|
||||
acc +42
|
||||
acc +0
|
||||
jmp +1
|
||||
jmp -170
|
||||
acc +14
|
||||
acc +19
|
||||
jmp -199
|
||||
nop +15
|
||||
acc -11
|
||||
acc +20
|
||||
jmp -161
|
||||
nop -348
|
||||
acc -6
|
||||
acc +49
|
||||
jmp -468
|
||||
acc +11
|
||||
jmp -413
|
||||
acc -11
|
||||
acc -1
|
||||
acc +45
|
||||
jmp -181
|
||||
jmp -380
|
||||
nop -128
|
||||
acc +40
|
||||
jmp -179
|
||||
acc -9
|
||||
acc +24
|
||||
jmp -358
|
||||
acc +50
|
||||
acc +13
|
||||
acc -15
|
||||
jmp +14
|
||||
acc +4
|
||||
acc +12
|
||||
jmp -365
|
||||
nop -269
|
||||
jmp -443
|
||||
nop -224
|
||||
jmp -108
|
||||
acc +46
|
||||
acc -11
|
||||
jmp -515
|
||||
acc -8
|
||||
nop -284
|
||||
jmp -444
|
||||
acc +15
|
||||
nop -11
|
||||
jmp -288
|
||||
acc +28
|
||||
acc +35
|
||||
jmp -416
|
||||
acc +27
|
||||
acc -8
|
||||
acc -10
|
||||
acc +0
|
||||
jmp -167
|
||||
acc -9
|
||||
acc +42
|
||||
acc +20
|
||||
jmp -63
|
||||
jmp -107
|
||||
acc -6
|
||||
jmp -335
|
||||
jmp -460
|
||||
acc -2
|
||||
jmp -420
|
||||
acc +27
|
||||
acc +6
|
||||
jmp -458
|
||||
acc +31
|
||||
nop +19
|
||||
nop -396
|
||||
jmp -479
|
||||
nop -234
|
||||
acc +42
|
||||
jmp -142
|
||||
jmp -511
|
||||
nop +28
|
||||
acc -9
|
||||
acc +36
|
||||
acc +38
|
||||
jmp +27
|
||||
acc -3
|
||||
acc +9
|
||||
acc -19
|
||||
acc +3
|
||||
jmp -133
|
||||
jmp -503
|
||||
jmp -267
|
||||
acc +40
|
||||
acc +41
|
||||
acc +13
|
||||
nop -492
|
||||
jmp -327
|
||||
jmp -339
|
||||
acc +17
|
||||
acc +4
|
||||
acc +45
|
||||
acc +13
|
||||
jmp -419
|
||||
acc +31
|
||||
acc +0
|
||||
acc +37
|
||||
acc -13
|
||||
jmp -210
|
||||
jmp -517
|
||||
acc -15
|
||||
jmp -47
|
||||
acc -16
|
||||
jmp -129
|
||||
acc +16
|
||||
nop -455
|
||||
nop -263
|
||||
jmp -74
|
||||
acc +5
|
||||
acc +20
|
||||
acc +45
|
||||
acc +23
|
||||
jmp -490
|
||||
jmp -53
|
||||
acc +40
|
||||
jmp +1
|
||||
acc -14
|
||||
acc -1
|
||||
jmp +1
|
||||
Loading…
Reference in New Issue