62 lines
1.5 KiB
Nix
62 lines
1.5 KiB
Nix
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{lib, ...}: input: let
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inherit (lib.strings) trim splitString toIntBase10;
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inherit (builtins) match elemAt filter length;
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# real
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width = 101;
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height = 103;
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# example
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# width = 11;
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# height = 7;
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getQuadrants = {width, height}: robots: let
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mid.x = width / 2;
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mid.y = height / 2;
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tl = robots |> filter ({pos, ...}: pos.x < mid.x && pos.y < mid.y);
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tr = robots |> filter ({pos, ...}: pos.x > mid.x && pos.y < mid.y);
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dl = robots |> filter ({pos, ...}: pos.x < mid.x && pos.y > mid.y);
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dr = robots |> filter ({pos, ...}: pos.x > mid.x && pos.y > mid.y);
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in {inherit tl tr dl dr;}
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;
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robots = input
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|> trim
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|> splitString "\n"
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|> map (line: line
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|> match ''p=([0-9]+),([0-9]+) v=(-?[0-9]+),(-?[0-9]+)''
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|> (nums: {
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pos = {
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x = elemAt nums 0 |> toIntBase10;
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y = elemAt nums 1 |> toIntBase10;
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};
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vel = {
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x = elemAt nums 2 |> toIntBase10;
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y = elemAt nums 3 |> toIntBase10;
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};
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})
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)
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;
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pass = time: {pos, vel}: let
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x = lib.mod (pos.x + (vel.x * time)) width;
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y = lib.mod (pos.y + (vel.y * time)) height;
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in {
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pos = {
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x = if x < 0 then width + x else x;
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y = if y < 0 then height + y else y;
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};
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# inherit vel;
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};
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in {
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inherit width height pass getQuadrants robots;
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part1result = robots
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|> map (pass 100)
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|> getQuadrants {inherit width height;}
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|> ({tl, tr, dr, dl}: (length tl) * (length tr) * (length dr) * (length dl))
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;
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}
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