diff --git a/AdventOfCode.lpi b/AdventOfCode.lpi
index f9cc1bf..f3c814a 100644
--- a/AdventOfCode.lpi
+++ b/AdventOfCode.lpi
@@ -85,6 +85,10 @@
+
+
+
+
diff --git a/AdventOfCode.lpr b/AdventOfCode.lpr
index 5d88d23..b355b57 100644
--- a/AdventOfCode.lpr
+++ b/AdventOfCode.lpr
@@ -26,7 +26,7 @@ uses
Classes, SysUtils, CustApp,
USolver,
UTrebuchet, UCubeConundrum, UGearRatios, UScratchcards, UGiveSeedFertilizer, UWaitForIt, UCamelCards,
- UHauntedWasteland, UNumberTheory, UMirageMaintenance, UPipeMaze, UCosmicExpansion, UHotSprings;
+ UHauntedWasteland, UNumberTheory, UMirageMaintenance, UPipeMaze, UCosmicExpansion, UHotSprings, UPointOfIncidence;
type
@@ -63,6 +63,7 @@ begin
engine.RunAndFree(TPipeMaze.Create);
engine.RunAndFree(TCosmicExpansion.Create);
engine.RunAndFree(THotSprings.Create);
+ engine.RunAndFree(TPointOfIncidence.Create);
engine.Free;
end;
diff --git a/solvers/UPointOfIncidence.pas b/solvers/UPointOfIncidence.pas
new file mode 100644
index 0000000..b4e9777
--- /dev/null
+++ b/solvers/UPointOfIncidence.pas
@@ -0,0 +1,186 @@
+{
+ Solutions to the Advent Of Code.
+ Copyright (C) 2023 Stefan Müller
+
+ This program is free software: you can redistribute it and/or modify it under
+ the terms of the GNU General Public License as published by the Free Software
+ Foundation, either version 3 of the License, or (at your option) any later
+ version.
+
+ This program is distributed in the hope that it will be useful, but WITHOUT
+ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ this program. If not, see .
+}
+
+unit UPointOfIncidence;
+
+{$mode ObjFPC}{$H+}
+
+interface
+
+uses
+ Classes, SysUtils, Generics.Collections, Math, USolver;
+
+type
+
+ { TPointOfIncidence }
+
+ TPointOfIncidence = class(TSolver)
+ private
+ FLines: TStringList;
+ FHorizontalMirrorCandidates, FVerticalMirrorCandidates: specialize TList;
+ procedure ProcessPatternLine(const ALine: string);
+ procedure VerifyHorizontalCandidates(const ANewLine: string);
+ procedure CheckForNewHorizontalCandidate(const ANewLine: string);
+ procedure VerifyVerticalCandidates(const ALine: string);
+ procedure InitializeNewVerticalCandidates(const AFirstLine: string);
+ procedure FinishPattern;
+ public
+ constructor Create;
+ destructor Destroy; override;
+ procedure ProcessDataLine(const ALine: string); override;
+ procedure Finish; override;
+ function GetDataFileName: string; override;
+ function GetPuzzleName: string; override;
+ end;
+
+implementation
+
+{ TPointOfIncidence }
+
+procedure TPointOfIncidence.ProcessPatternLine(const ALine: string);
+begin
+ VerifyHorizontalCandidates(ALine);
+ CheckForNewHorizontalCandidate(ALine);
+
+ if FLines.Count > 0 then
+ VerifyVerticalCandidates(ALine)
+ else
+ InitializeNewVerticalCandidates(ALine);
+
+ FLines.Add(ALine);
+end;
+
+procedure TPointOfIncidence.VerifyHorizontalCandidates(const ANewLine: string);
+var
+ i, mirroredIndex: Integer;
+begin
+ // Checks if the current line fulfills the exisiting horizontal mirror candidates.
+ i := FHorizontalMirrorCandidates.Count - 1;
+ while i >= 0 do
+ begin
+ // Calculates the index of the line that the current line would be a duplicate of in regards to the i-th candidate.
+ mirroredIndex := 2 * FHorizontalMirrorCandidates[i] - FLines.Count - 1;
+ if (mirroredIndex >= 0) and (ANewLine <> FLines[mirroredIndex]) then
+ FHorizontalMirrorCandidates.Delete(i);
+ Dec(i);
+ end;
+end;
+
+procedure TPointOfIncidence.CheckForNewHorizontalCandidate(const ANewLine: string);
+begin
+ // Checks for new horizontal mirror candidate between ALine and the previous line.
+ if (FLines.Count > 0) and (ANewLine = FLines[FLines.Count - 1]) then
+ FHorizontalMirrorCandidates.Add(FLines.Count);
+end;
+
+procedure TPointOfIncidence.VerifyVerticalCandidates(const ALine: string);
+var
+ i, j, len, mirror: Integer;
+begin
+ // Checks if the current line fulfills the exisiting vertical mirror candidates.
+ len := Length(ALine);
+ i := FVerticalMirrorCandidates.Count - 1;
+ while i >= 0 do
+ begin
+ mirror := FVerticalMirrorCandidates[i];
+ for j := 0 to Min(mirror - 1, len - mirror - 1) do
+ begin
+ if ALine[mirror - j] <> ALine[mirror + j + 1] then
+ begin
+ FVerticalMirrorCandidates.Delete(i);
+ Break;
+ end;
+ end;
+ Dec(i);
+ end;
+end;
+
+procedure TPointOfIncidence.InitializeNewVerticalCandidates(const AFirstLine: string);
+var
+ i, j, len: Integer;
+ isMirror: Boolean;
+begin
+ // Checks the line for vertical mirror candidates, i.e. mirrors that work for this line.
+ len := Length(AFirstLine);
+ for i := 1 to len - 1 do begin
+ isMirror := True;
+ for j := 0 to Min(i - 1, len - i - 1) do
+ begin
+ if AFirstLine[i - j] <> AFirstLine[i + j + 1] then
+ begin
+ isMirror := False;
+ Break;
+ end;
+ end;
+ if isMirror then
+ FVerticalMirrorCandidates.Add(i);
+ end;
+end;
+
+procedure TPointOfIncidence.FinishPattern;
+var
+ i: Integer;
+begin
+ for i := 0 to FHorizontalMirrorCandidates.Count - 1 do
+ Inc(FPart1, FHorizontalMirrorCandidates[i] * 100);
+ for i := 0 to FVerticalMirrorCandidates.Count - 1 do
+ Inc(FPart1, FVerticalMirrorCandidates[i]);
+ FLines.Clear;
+ FHorizontalMirrorCandidates.Clear;
+ FVerticalMirrorCandidates.Clear;
+end;
+
+constructor TPointOfIncidence.Create;
+begin
+ FLines := TStringList.Create;
+ FHorizontalMirrorCandidates := specialize TList.Create;
+ FVerticalMirrorCandidates := specialize TList.Create;
+end;
+
+destructor TPointOfIncidence.Destroy;
+begin
+ FLines.Free;
+ FHorizontalMirrorCandidates.Free;
+ FVerticalMirrorCandidates.Free;
+ inherited Destroy;
+end;
+
+procedure TPointOfIncidence.ProcessDataLine(const ALine: string);
+begin
+ if ALine <> '' then
+ ProcessPatternLine(ALine)
+ else
+ FinishPattern;
+end;
+
+procedure TPointOfIncidence.Finish;
+begin
+ FinishPattern;
+end;
+
+function TPointOfIncidence.GetDataFileName: string;
+begin
+ Result := 'point_of_incidence.txt';
+end;
+
+function TPointOfIncidence.GetPuzzleName: string;
+begin
+ Result := 'Day 13: Point of Incidence';
+end;
+
+end.
+
diff --git a/tests/AdventOfCodeFPCUnit.lpi b/tests/AdventOfCodeFPCUnit.lpi
index 178fda6..9282724 100644
--- a/tests/AdventOfCodeFPCUnit.lpi
+++ b/tests/AdventOfCodeFPCUnit.lpi
@@ -92,6 +92,10 @@
+
+
+
+
diff --git a/tests/AdventOfCodeFPCUnit.lpr b/tests/AdventOfCodeFPCUnit.lpr
index 896d2ac..ecd15fb 100644
--- a/tests/AdventOfCodeFPCUnit.lpr
+++ b/tests/AdventOfCodeFPCUnit.lpr
@@ -6,7 +6,7 @@ uses
Interfaces, Forms, GuiTestRunner, USolver, UBaseTestCases, UTrebuchetTestCases, UCubeConundrumTestCases,
UGearRatiosTestCases, UScratchcardsTestCases, UGiveSeedFertilizerTestCases, UWaitForItTestCases, UCamelCardsTestCases,
UHauntedWastelandTestCases, UMirageMaintenanceTestCases, UPipeMazeTestCases, UCosmicExpansionTestCases,
- UHotSpringsTestCases;
+ UHotSpringsTestCases, UPointOfIncidenceTestCases;
{$R *.res}
diff --git a/tests/UPointOfIncidenceTestCases.pas b/tests/UPointOfIncidenceTestCases.pas
new file mode 100644
index 0000000..afc44dd
--- /dev/null
+++ b/tests/UPointOfIncidenceTestCases.pas
@@ -0,0 +1,78 @@
+{
+ Solutions to the Advent Of Code.
+ Copyright (C) 2023 Stefan Müller
+
+ This program is free software: you can redistribute it and/or modify it under
+ the terms of the GNU General Public License as published by the Free Software
+ Foundation, either version 3 of the License, or (at your option) any later
+ version.
+
+ This program is distributed in the hope that it will be useful, but WITHOUT
+ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ this program. If not, see .
+}
+
+unit UPointOfIncidenceTestCases;
+
+{$mode ObjFPC}{$H+}
+
+interface
+
+uses
+ Classes, SysUtils, fpcunit, testregistry, USolver, UBaseTestCases, UPointOfIncidence;
+
+type
+
+ { TPointOfIncidenceFullDataTestCase }
+
+ TPointOfIncidenceFullDataTestCase = class(TEngineBaseTest)
+ protected
+ function CreateSolver: ISolver; override;
+ published
+ procedure TestPart1;
+ end;
+
+ { TPointOfIncidenceExampleTestCase }
+
+ TPointOfIncidenceExampleTestCase = class(TExampleEngineBaseTest)
+ protected
+ function CreateSolver: ISolver; override;
+ published
+ procedure TestPart1;
+ end;
+
+implementation
+
+{ TPointOfIncidenceFullDataTestCase }
+
+function TPointOfIncidenceFullDataTestCase.CreateSolver: ISolver;
+begin
+ Result := TPointOfIncidence.Create;
+end;
+
+procedure TPointOfIncidenceFullDataTestCase.TestPart1;
+begin
+ AssertEquals(37718, FSolver.GetResultPart1);
+end;
+
+{ TPointOfIncidenceExampleTestCase }
+
+function TPointOfIncidenceExampleTestCase.CreateSolver: ISolver;
+begin
+ Result := TPointOfIncidence.Create;
+end;
+
+procedure TPointOfIncidenceExampleTestCase.TestPart1;
+begin
+ AssertEquals(405, FSolver.GetResultPart1);
+end;
+
+initialization
+
+ RegisterTest(TPointOfIncidenceFullDataTestCase);
+ RegisterTest(TPointOfIncidenceExampleTestCase);
+end.
+