129 lines
3.4 KiB
Plaintext
129 lines
3.4 KiB
Plaintext
{
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Solutions to the Advent Of Code.
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Copyright (C) 2023 Stefan Müller
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This program is free software: you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program. If not, see <http://www.gnu.org/licenses/>.
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}
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unit UNeverTellMeTheOdds;
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{$mode ObjFPC}{$H+}
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interface
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uses
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Classes, SysUtils, Generics.Collections, Math, USolver;
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type
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{ THailstone }
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THailstone = record
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X, Y, Z: Int64;
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VX, VY, VZ: Integer;
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end;
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THailstones = specialize TList<THailstone>;
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{ TNeverTellMeTheOdds }
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TNeverTellMeTheOdds = class(TSolver)
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private
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FMin, FMax: Int64;
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FHailStones: THailstones;
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function AreIntersecting(constref AHailstone1, AHailstone2: THailstone): Boolean;
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public
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constructor Create(const AMin: Int64 = 200000000000000; const AMax: Int64 = 400000000000000);
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destructor Destroy; override;
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procedure ProcessDataLine(const ALine: string); override;
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procedure Finish; override;
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function GetDataFileName: string; override;
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function GetPuzzleName: string; override;
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end;
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implementation
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{ TNeverTellMeTheOdds }
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function TNeverTellMeTheOdds.AreIntersecting(constref AHailstone1, AHailstone2: THailstone): Boolean;
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var
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m1, m2, x, y: Double;
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begin
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Result := False;
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m1 := AHailstone1.VY / AHailstone1.VX;
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m2 := AHailstone2.VY / AHailstone2.VX;
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if m1 <> m2 then
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begin
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x := (AHailstone2.Y - m2 * AHailstone2.X - AHailstone1.Y + m1 * AHailstone1.X) / (m1 - m2);
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if (FMin <= x) and (x <= FMax)
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and (x * Sign(AHailstone1.VX) >= AHailstone1.X * Sign(AHailstone1.VX))
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and (x * Sign(AHailstone2.VX) >= AHailstone2.X * Sign(AHailstone2.VX)) then
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begin
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y := m1 * (x - AHailstone1.X) + AHailstone1.Y;
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if (FMin <= y) and (y <= FMax) then
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Result := True
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end;
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end;
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end;
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constructor TNeverTellMeTheOdds.Create(const AMin: Int64; const AMax: Int64);
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begin
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FMin := AMin;
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FMax := AMax;
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FHailStones := THailstones.Create;
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end;
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destructor TNeverTellMeTheOdds.Destroy;
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begin
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FHailStones.Free;
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inherited Destroy;
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end;
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procedure TNeverTellMeTheOdds.ProcessDataLine(const ALine: string);
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var
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split: TStringArray;
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hailstone: THailstone;
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begin
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split := ALine.Split([',', '@']);
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hailstone.X := StrToInt64(Trim(split[0]));
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hailstone.Y := StrToInt64(Trim(split[1]));
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hailstone.Z := StrToInt64(Trim(split[2]));
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hailstone.VX := StrToInt(Trim(split[3]));
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hailstone.VY := StrToInt(Trim(split[4]));
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hailstone.VZ := StrToInt(Trim(split[5]));
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FHailStones.Add(hailstone);
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end;
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procedure TNeverTellMeTheOdds.Finish;
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var
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i, j: Integer;
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begin
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for i := 0 to FHailStones.Count - 2 do
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for j := i + 1 to FHailStones.Count - 1 do
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if AreIntersecting(FHailStones[i], FHailStones[j]) then
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Inc(FPart1);
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end;
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function TNeverTellMeTheOdds.GetDataFileName: string;
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begin
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Result := 'never_tell_me_the_odds.txt';
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end;
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function TNeverTellMeTheOdds.GetPuzzleName: string;
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begin
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Result := 'Day 24: Never Tell Me The Odds';
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end;
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end.
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