95 lines
2.7 KiB
Erlang
95 lines
2.7 KiB
Erlang
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-module(day13).
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-export([start/0]).
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calc_severity(Input)
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-> CalcMap = lists:foldl(fun(X, Sum) ->
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[Index|Depth] = re:split(X, ": "),
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{ IndexInt, _ } = string:to_integer(Index),
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{ DepthInt, _ } = string:to_integer(Depth),
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maps:put(IndexInt, DepthInt, Sum)
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end, maps:new(), re:split(Input, "\n")),
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LastStep = lists:max(maps:keys(CalcMap)),
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InitialSeverity = calc_severity(CalcMap, update_positions(CalcMap, 0), 0, 0, LastStep, 0),
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SafeDelay = calc_delay(CalcMap, LastStep, 0),
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{ InitialSeverity, SafeDelay }.
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calc_delay(CalcMap, LastStep, Delay)
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-> PositionMap = update_positions(CalcMap, Delay),
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CurrentSeverity = calc_delay(CalcMap, PositionMap, Delay, 0, LastStep),
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if CurrentSeverity == 0 -> Delay;
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true -> calc_delay(CalcMap, LastStep, Delay + 1)
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end.
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calc_delay(_CalcMap, _PositionMap, _Picosecond, PacketIndex, LastStep)
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when PacketIndex > LastStep -> 0;
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calc_delay(CalcMap, PositionMap, Picosecond, PacketIndex, LastStep)
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-> CurrentPosition = maps:get(PacketIndex, PositionMap, -1),
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if CurrentPosition == 0 -> 1;
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true -> calc_delay(CalcMap, update_positions(CalcMap, Picosecond + 1), Picosecond + 1, PacketIndex + 1, LastStep)
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end.
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calc_severity(_CalcMap, _PositionMap, _Picosecond, PacketIndex, LastStep, Score)
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when PacketIndex > LastStep -> Score;
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calc_severity(CalcMap, PositionMap, Picosecond, PacketIndex, LastStep, Score)
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-> CurrentPosition = maps:get(PacketIndex, PositionMap, -1),
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UpdatedPositions = update_positions(CalcMap, Picosecond + 1),
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if CurrentPosition == 0 -> calc_severity(CalcMap, UpdatedPositions, Picosecond + 1, PacketIndex + 1, LastStep, Score + (PacketIndex * maps:get(PacketIndex, CalcMap)));
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true -> calc_severity(CalcMap, UpdatedPositions, Picosecond + 1, PacketIndex + 1, LastStep, Score)
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end.
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update_positions(CalcMap, Picosecond)
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-> lists:foldl(fun(X, Sum) ->
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CurrentDepth = maps:get(X, CalcMap),
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if (Picosecond div (CurrentDepth - 1)) rem 2 == 0 -> maps:put(X, (Picosecond rem (CurrentDepth - 1)), Sum);
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true -> maps:put(X, (CurrentDepth - (Picosecond rem CurrentDepth)), Sum)
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end
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end, maps:new(), maps:keys(CalcMap)).
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start()
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-> io:fwrite("~p~n", [calc_severity("0: 3
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1: 2
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4: 4
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6: 4")]),
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io:fwrite("~p~n", [calc_severity("0: 3
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1: 2
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2: 4
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4: 6
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6: 4
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8: 6
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10: 5
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12: 6
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14: 9
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16: 6
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18: 8
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20: 8
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22: 8
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24: 8
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26: 8
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28: 8
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30: 12
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32: 14
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34: 10
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36: 12
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38: 12
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40: 10
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42: 12
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44: 12
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46: 12
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48: 12
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50: 12
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52: 14
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54: 14
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56: 12
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62: 12
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64: 14
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66: 14
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68: 14
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70: 17
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72: 14
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74: 14
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76: 14
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82: 14
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86: 18
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88: 14
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96: 14
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98: 44")]).
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