Merged solution for "Day 12: Hot Springs", part 2

AdventOfCode.lpi

@@ -157,6 +157,14 @@
         <Filename Value="UCommon.pas"/>
         <IsPartOfProject Value="True"/>
       </Unit>
+      <Unit>
+        <Filename Value="UMultiIndexEnumerator.pas"/>
+        <IsPartOfProject Value="True"/>
+      </Unit>
+      <Unit>
+        <Filename Value="UBinomialCoefficients.pas"/>
+        <IsPartOfProject Value="True"/>
+      </Unit>
     </Units>
   </ProjectOptions>
   <CompilerOptions>

UBinomialCoefficients.pas

@@ -0,0 +1,105 @@
+{
+  Solutions to the Advent Of Code.
+  Copyright (C) 2024  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 <http://www.gnu.org/licenses/>.
+}
+
+unit UBinomialCoefficients;
+
+{$mode ObjFPC}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils, Generics.Collections;
+
+type
+  TCardinalArray = array of Cardinal;
+  TCardinalArrays = specialize TList<TCardinalArray>;
+
+  { TBinomialCoefficientCache }
+
+  TBinomialCoefficientCache = class
+  private
+    FCache: TCardinalArrays;
+    procedure AddRow;
+  public
+    constructor Create;
+    destructor Destroy; override;
+    // Returns N choose K, with N >= K >= 0.
+    function Get(const AN, AK: Cardinal): Cardinal;
+    // Returns the number of cached rows C = N + 1, where N is the highest from previously queried "N choose K". The
+    // actual number of cached binomial coefficient values is C * (C + 1) / 2.
+    function GetCachedRowsCount: Cardinal;
+  end;
+
+var
+  BinomialCoefficients: TBinomialCoefficientCache;
+
+implementation
+
+{ TBinomialCoefficientCache }
+
+procedure TBinomialCoefficientCache.AddRow;
+var
+  row: TCardinalArray;
+  i: Cardinal;
+begin
+  SetLength(row, FCache.Count + 1);
+  row[0] := 1;
+  if FCache.Count > 0 then
+  begin
+    row[FCache.Count] := 1;
+    for i := 1 to FCache.Count - 1 do
+      row[i] := FCache.Last[i - 1] + FCache.Last[i];
+  end;
+  FCache.Add(row);
+end;
+
+constructor TBinomialCoefficientCache.Create;
+begin
+  FCache := TCardinalArrays.Create;
+end;
+
+destructor TBinomialCoefficientCache.Destroy;
+begin
+  FCache.Free;
+  inherited Destroy;
+end;
+
+function TBinomialCoefficientCache.Get(const AN, AK: Cardinal): Cardinal;
+var
+  i: Cardinal;
+begin
+  if AN < AK then
+    raise ERangeError.Create('Cannot calculate binomial coefficient "n choose k" with k larger than n.');
+
+  for i := FCache.Count to AN do
+    AddRow;
+  Result := FCache[AN][AK];
+end;
+
+function TBinomialCoefficientCache.GetCachedRowsCount: Cardinal;
+begin
+  Result := FCache.Count;
+end;
+
+initialization
+  BinomialCoefficients := TBinomialCoefficientCache.Create;
+
+finalization
+  BinomialCoefficients.Free;
+
+end.
+

UCommon.pas

@@ -40,6 +40,7 @@ const
   CPCardinalDirections: array[0..3] of PPoint = (@CDirectionRight, @CDirectionDown, @CDirectionLeft, @CDirectionUp);
 
 type
+  TInt64Array = array of Int64;
   TIntegerList = specialize TList<Integer>;
   TPoints = specialize TList<TPoint>;
 

UMultiIndexEnumerator.pas

@@ -0,0 +1,161 @@
+{
+  Solutions to the Advent Of Code.
+  Copyright (C) 2024  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 <http://www.gnu.org/licenses/>.
+}
+
+unit UMultiIndexEnumerator;
+
+{$mode ObjFPC}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils;
+
+type
+  TIndexArray = array of Integer;
+
+  TIndexValidationResult = (ivrValid, ivrSkip, ivrBacktrack);
+
+  TEnumerableMultiIndexStrategy = class;
+
+  { TMultiIndexEnumerator }
+
+  TMultiIndexEnumerator = class(TInterfacedObject, specialize IEnumerator<TIndexArray>)
+  private
+    FStrategy: TEnumerableMultiIndexStrategy;
+    FCurrent: TIndexArray;
+    FMustInit: Boolean;
+    function UpdateArray(const AInit: Boolean): Boolean;
+  public
+    constructor Create(const AStrategy: TEnumerableMultiIndexStrategy);
+    function GetCurrent: TIndexArray;
+    function MoveNext: Boolean;
+    procedure Reset;
+    property Current: TIndexArray read GetCurrent;
+  end;
+
+  { TEnumerableMultiIndexStrategy }
+
+  TEnumerableMultiIndexStrategy = class(TInterfacedObject, specialize IEnumerable<TIndexArray>)
+  public
+    function GetEnumerator: specialize IEnumerator<TIndexArray>;
+    // Returns the number of indices to iterate over, must return positive (non-zero) value.
+    function GetCardinality: Integer; virtual; abstract;
+    function TryGetStartIndexValue(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer;
+      out AStartIndexValue: Integer): Boolean; virtual; abstract;
+    function ValidateIndexValue(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer):
+      TIndexValidationResult; virtual; abstract;
+  end;
+
+implementation
+
+{ TMultiIndexEnumerator }
+
+function TMultiIndexEnumerator.UpdateArray(const AInit: Boolean): Boolean;
+var
+  i, initialized: Integer;
+  r: TIndexValidationResult;
+begin
+  if AInit then
+  begin
+    i := 0;
+    initialized := -1;
+  end
+  else begin
+    i := Length(FCurrent) - 1;
+    initialized := i;
+  end;
+
+  while i < Length(FCurrent) do
+  begin
+    if initialized < i then
+    begin
+      // Checks whether start index value can be set, and backtracks or aborts if not.
+      if not FStrategy.TryGetStartIndexValue(FCurrent, i, FCurrent[i]) then
+        if i > 0 then
+        begin
+          Dec(i);
+          Continue;
+        end
+        else begin
+          Result := False;
+          Exit;
+        end
+    end
+    else
+      // Sets next candidate for current index value.
+      Inc(FCurrent[i]);
+
+    // Checks if current index value is valid, and increases it until it is, or backtracks or aborts if so indicated.
+    while True do
+    begin
+      r := FStrategy.ValidateIndexValue(FCurrent, i);
+      case r of
+        ivrValid: begin
+          initialized := i;
+          Inc(i);
+          Break;
+        end;
+        ivrSkip:
+          Inc(FCurrent[i]);
+        ivrBacktrack:
+          if i > 0 then
+          begin
+            Dec(i);
+            Break;
+          end
+          else begin
+            Result := False;
+            Exit;
+          end;
+      end;
+    end;
+  end;
+  Result := True;
+end;
+
+constructor TMultiIndexEnumerator.Create(const AStrategy: TEnumerableMultiIndexStrategy);
+begin
+  FStrategy := AStrategy;
+  SetLength(FCurrent, FStrategy.GetCardinality);
+  Reset;
+end;
+
+function TMultiIndexEnumerator.GetCurrent: TIndexArray;
+begin
+  Result := FCurrent;
+end;
+
+function TMultiIndexEnumerator.MoveNext: Boolean;
+begin
+  Result := UpdateArray(FMustInit);
+  FMustInit := False;
+end;
+
+procedure TMultiIndexEnumerator.Reset;
+begin
+  FMustInit := True;
+end;
+
+{ TEnumerableMultiIndexStrategy }
+
+function TEnumerableMultiIndexStrategy.GetEnumerator: specialize IEnumerator<TIndexArray>;
+begin
+  Result := TMultiIndexEnumerator.Create(Self);
+end;
+
+end.
+

solvers/UHotSprings.pas

@@ -1,6 +1,6 @@
 {
   Solutions to the Advent Of Code.
-  Copyright (C) 2023  Stefan Müller
+  Copyright (C) 2023-2024  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
@@ -22,27 +22,176 @@ unit UHotSprings;
 interface
 
 uses
-  Classes, SysUtils, Generics.Collections, USolver;
+  Classes, SysUtils, Math, Generics.Collections, USolver, UCommon, UMultiIndexEnumerator, UBinomialCoefficients;
 
 const
   COperationalChar = '.';
   CDamagedChar = '#';
   CWildcardChar = '?';
-  COperationalPatternChars = [COperationalChar, CWildcardChar];
+  CPart2Repetition = 5;
-  CDamagedPatternChars = [CDamagedChar, CWildcardChar];
 
 type
+  TValidationLengths = array of array of Integer;
+
+  { TDamage }
+
+  TDamage = record
+    Start, Length, CharsRemaining: Integer;
+  end;
+  TDamages = specialize TList<TDamage>;
+
+  TBlockCombinationsCache = specialize THashMap<Int64, Int64>;
+  TCombinationsCache = specialize TObjectHashMap<string, TBlockCombinationsCache>;
+
+  { TBlock }
+
+  TBlock = class
+  private
+    FPattern: string;
+    FDamages: TDamages;
+    FCombinationsCache: TBlockCombinationsCache;
+    procedure ParseDamages;
+  public
+    constructor Create(const APattern: string; constref ACombinationsCache: TBlockCombinationsCache);
+    destructor Destroy; override;
+    property Pattern: string read FPattern;
+    // List of damages in this block, containing exactly one entry for each sequence of consecutive damage characters in
+    // the block's pattern, ordered such that a damage with lower index is further left.
+    // For example, if Pattern is '??##?#?', then Damages would have 2 entries.
+    property Damages: TDamages read FDamages;
+    property CombinationsCache: TBlockCombinationsCache read FCombinationsCache;
+  end;
+  TBlocks = specialize TObjectList<TBlock>;
+
+  { TAccumulatedCombinationsMultiIndexStrategy }
+
+  // Adds accumulated combinations to the enumerable strategy to allow calculation of combinations on the fly, and
+  // therefore early rejection of invalid multi-index configurations.
+  TAccumulatedCombinationsMultiIndexStrategy = class(TEnumerableMultiIndexStrategy)
+  private
+    FAccumulatedCombinations: TInt64Array;
+  protected
+    function CalcCombinations(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer): Int64; virtual;
+      abstract;
+    function UpdateCombinations(const AValidationResult: TIndexValidationResult; constref ACurrentIndexArray:
+      TIndexArray; const ACurrentIndex: Integer): TIndexValidationResult;
+  public
+    function GetCombinations: Int64;
+  end;
+
+  TConditionRecord = class;
+
+  { TValidationsToBlockAssignments }
+
+  // Enumerable strategy that enumerates all valid assignments of ranges of validation numbers to individual blocks in
+  // the form of start and stop indices.
+  TValidationsToBlockAssignments = class(TAccumulatedCombinationsMultiIndexStrategy)
+  private
+    FConditionRecord: TConditionRecord;
+  protected
+    function CalcCombinations(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer): Int64; override;
+  public
+    constructor Create(constref AConditionRecord: TConditionRecord);
+    function GetCardinality: Integer; override;
+    function TryGetStartIndexValue(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer;
+      out AStartIndexValue: Integer): Boolean; override;
+    function ValidateIndexValue(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer):
+      TIndexValidationResult; override;
+  end;
+
+  { TDamageToValidationAssignments }
+
+  // Enumerable strategy that enumerates all valid assignments of each damage in the block to a specific validation
+  // number from the validation numbers that have been assigned to the block, as indicated by start and stop indices.
+  TDamageToValidationAssignments = class(TEnumerableMultiIndexStrategy)
+  private
+    FConditionRecord: TConditionRecord;
+    FBlock: TBlock;
+    FValidationStartIndex, FValidationStopIndex: Integer;
+    // Calculates "span", the length of all damages for one validation number combined.
+    function CalcValidationSpan(constref ACurrentIndexArray: TIndexArray; const ALastDamageIndex, AValidationNumber:
+      Integer): Integer;
+  public
+    constructor Create(constref AConditionRecord: TConditionRecord; constref ABlock: TBlock;
+      const AStartValidationIndex, AStopValidationIndex: Integer);
+    function GetCardinality: Integer; override;
+    function TryGetStartIndexValue(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer;
+      out AStartIndexValue: Integer): Boolean; override;
+    function ValidateIndexValue(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer):
+      TIndexValidationResult; override;
+  end;
+
+  { TValidationPositionInfo }
+
+  TValidationPositionInfo = record
+    ValidationIndex, MinStart, MaxStart: Integer;
+  end;
+
+  TValidationPositionInfos = specialize TList<TValidationPositionInfo>;
+
+  { TValidationPositionOffsets }
+
+  // Enumerable strategy that enumerates all valid assignments of start positions (positions mean character indices in
+  // the block patterns) of validation numbers that have been assigned to damages in the current block, as indicated by
+  // provided TValidationPositionInfos.
+  TValidationPositionOffsets = class(TAccumulatedCombinationsMultiIndexStrategy)
+  private
+    FConditionRecord: TConditionRecord;
+    FPositionInfos: TValidationPositionInfos;
+    FBlockLength, FValidationStartIndex, FValidationStopIndex: Integer;
+  protected
+    function CalcCombinations(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer): Int64; override;
+  public
+    constructor Create(constref AConditionRecord: TConditionRecord; constref APositionInfos: TValidationPositionInfos;
+      const ABlockLength, AValidationStartIndex, AValidationStopIndex: Integer);
+    function GetCardinality: Integer; override;
+    function TryGetStartIndexValue(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer;
+      out AStartIndexValue: Integer): Boolean; override;
+    function ValidateIndexValue(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer):
+      TIndexValidationResult; override;
+  end;
+
+  { TConditionRecord }
+
+  TConditionRecord = class
+  private
+    // List of validation numbers as stated in the problem input.
+    FValidation: TIntegerList;
+    // List of non-empty, maximum-length parts of the pattern without operational springs ("blocks").
+    FBlocks: TBlocks;
+    // Array 'a' of accumulated validation series lengths. 'a[i, j]' denotes the combined length of consecutive
+    // validation numbers from 'FValidation[i]' to 'FValidation[j - 1]' with a single space in between each pair of
+    // them.
+    FValidationLengths: TValidationLengths;
+    // Array 'a' of minimum indices 'a[i]', such that all remaining validation numbers starting at index 'a[i] - 1'
+    // cannot fit into the remaining blocks starting at 'FBlocks[i]'.
+    FMinIndices: TIndexArray;
+    FCombinationsCache: TCombinationsCache;
+    procedure InitValidationLengths;
+    procedure InitMinIndices;
+    function CalcCombinationsBlockSingleValidation(constref ABlock: TBlock; const AIndex: Integer): Int64;
+    function CalcCombinationsBlockMultiValidations(constref ABlock: TBlock; constref AIndices: TIndexArray;
+      const AStartIndex, AStopIndex: Integer): Int64;
+    function CalcValidationsId(const AStartIndex, AStopIndex: Integer): Int64;
+  public
+    constructor Create(constref ACombinationsCache: TCombinationsCache);
+    destructor Destroy; override;
+    // Adds all non-empty, maximum-length parts of the pattern without operational springs ("blocks").
+    procedure AddBlocks(const APattern: string);
+    function GenerateBlockAssignments: Int64;
+    function CalcCombinationsBlock(constref ABlock: TBlock; const AStartIndex, AStopIndex: Integer): Int64;
+    function CalcCombinationsWildcardSequence(const ASequenceLength, AStartIndex, AStopIndex: Integer): Int64;
+    property Validation: TIntegerList read FValidation;
+    property Blocks: TBlocks read FBlocks;
+    property ValidationLengths: TValidationLengths read FValidationLengths;
+    property MinIndices: TIndexArray read FMinIndices;
+  end;
 
   { THotSprings }
 
   THotSprings = class(TSolver)
   private
-    FValidation: specialize TList<Integer>;
+    FCombinationsCache: TCombinationsCache;
-    FSpringPattern: string;
-    procedure ExtendArrangement(const AArrangement: string; const ARemainingFreeOperationalCount, ACurrentValidationIndex:
-      Integer);
-    function TryAppendOperationalChar(var AArrangement: string): Boolean;
-    function TryAppendValidationBlock(var AArrangement: string; const ALength: Integer): Boolean;
   public
     constructor Create;
     destructor Destroy; override;
@@ -54,99 +203,549 @@ type
 
 implementation
 
-{ THotSprings }
+{ TBlock }
 
-procedure THotSprings.ExtendArrangement(const AArrangement: string; const ARemainingFreeOperationalCount,
+procedure TBlock.ParseDamages;
-  ACurrentValidationIndex: Integer);
-var
-  match: Boolean;
-  temp: string;
-begin
-  if Length(AArrangement) = Length(FSpringPattern) then
-    Inc(FPart1)
-  else begin
-    temp := AArrangement;
-    // Tries to append a dot (operational) to the current arrangement.
-    if (ARemainingFreeOperationalCount > 0) and TryAppendOperationalChar(temp) then
-    begin
-      ExtendArrangement(temp, ARemainingFreeOperationalCount - 1, ACurrentValidationIndex);
-    end;
-
-    // Tries to append the current validation block (damaged) to the current arrangement.
-    if ACurrentValidationIndex < FValidation.Count then
-    begin
-      temp := AArrangement;
-      match := TryAppendValidationBlock(temp, FValidation[ACurrentValidationIndex]);
-
-      // ... and the mandatory dot after the block, if it is not the last block.
-      if match
-      and (ACurrentValidationIndex < FValidation.Count - 1)
-      and not TryAppendOperationalChar(temp) then
-        match := False;
-
-      if match then
-        ExtendArrangement(temp, ARemainingFreeOperationalCount, ACurrentValidationIndex + 1);
-    end;
-  end;
-end;
-
-function THotSprings.TryAppendOperationalChar(var AArrangement: string): Boolean;
-begin
-  if FSpringPattern[Length(AArrangement) + 1] in COperationalPatternChars then
-  begin
-    AArrangement := AArrangement + COperationalChar;
-    Result := True;
-  end
-  else
-    Result := False;
-end;
-
-function THotSprings.TryAppendValidationBlock(var AArrangement: string; const ALength: Integer): Boolean;
 var
   i, len: Integer;
+  damage: TDamage;
 begin
-  Result := True;
+  FDamages := TDamages.Create;
-  len := Length(AArrangement);
+  damage.Length := 0;
-  for i := 1 to ALength do
+  len := Length(FPattern);
+  for i := 1 to len do
+    // The pattern must only contain damage and wildcard characters here.
+    if FPattern[i] = CDamagedChar then
     begin
-    if FSpringPattern[len + i] in CDamagedPatternChars then
+      if damage.Length = 0 then
-      AArrangement := AArrangement + CDamagedChar
+        damage.Start := i;
+      Inc(damage.Length);
+    end
+    else if damage.Length > 0 then
+    begin
+      damage.CharsRemaining := len - damage.Start - damage.Length + 1;
+      FDamages.Add(damage);
+      damage.Length := 0;
+    end;
+
+  if damage.Length > 0 then
+  begin
+    damage.CharsRemaining := 0;
+    FDamages.Add(damage);
+  end;
+end;
+
+constructor TBlock.Create(const APattern: string; constref ACombinationsCache: TBlockCombinationsCache);
+begin
+  FPattern := APattern;
+  FCombinationsCache := ACombinationsCache;
+  ParseDamages;
+end;
+
+destructor TBlock.Destroy;
+begin
+  FDamages.Free;
+  inherited Destroy;
+end;
+
+{ TAccumulatedCombinationsMultiIndexStrategy }
+
+function TAccumulatedCombinationsMultiIndexStrategy.UpdateCombinations(const AValidationResult: TIndexValidationResult;
+  constref ACurrentIndexArray: TIndexArray; const ACurrentIndex: Integer): TIndexValidationResult;
+var
+  combinations: Int64;
+begin
+  Result := AValidationResult;
+  if Result = ivrValid then
+  begin
+    combinations := CalcCombinations(ACurrentIndexArray, ACurrentIndex);
+    if combinations = 0 then
+      Result := ivrSkip
+    else if ACurrentIndex > 0 then
+      FAccumulatedCombinations[ACurrentIndex] := combinations * FAccumulatedCombinations[ACurrentIndex - 1]
     else begin
-      Result := False;
+      SetLength(FAccumulatedCombinations, GetCardinality);
-      Break;
+      FAccumulatedCombinations[ACurrentIndex] := combinations;
     end;
   end;
 end;
 
+function TAccumulatedCombinationsMultiIndexStrategy.GetCombinations: Int64;
+begin
+  if FAccumulatedCombinations <> nil then
+    Result := FAccumulatedCombinations[GetCardinality - 1]
+  else
+    Result := 0;
+end;
+
+{ TValidationsToBlockAssignments }
+
+function TValidationsToBlockAssignments.CalcCombinations(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex:
+  Integer): Int64;
+var
+  block: TBlock;
+  start, stop: Integer;
+begin
+  // 'ACurrentIndexArray[i] - 1' denotes the index of the last validation number assigned to 'Block[i]', and the index
+  // of the first validation number in 'Validation' assigned to 'Block[i + 1]'. If two consecutive values in
+  // 'ACurrentIndexArray' are the same, then the block in between has no numbers assigned to it.
+  block := FConditionRecord.Blocks[ACurrentIndex];
+  if ACurrentIndex > 0 then
+    start := ACurrentIndexArray[ACurrentIndex - 1]
+  else
+    start := 0;
+  stop := ACurrentIndexArray[ACurrentIndex] - 1;
+  if block.Damages.Count > 0 then
+    Result := FConditionRecord.CalcCombinationsBlock(block, start, stop)
+  else
+    Result := FConditionRecord.CalcCombinationsWildcardSequence(Length(block.Pattern), start, stop);
+end;
+
+constructor TValidationsToBlockAssignments.Create(constref AConditionRecord: TConditionRecord);
+begin
+  FConditionRecord := AConditionRecord;
+end;
+
+function TValidationsToBlockAssignments.GetCardinality: Integer;
+begin
+  Result := FConditionRecord.Blocks.Count;
+end;
+
+function TValidationsToBlockAssignments.TryGetStartIndexValue(constref ACurrentIndexArray: TIndexArray;
+  const ACurrentIndex: Integer; out AStartIndexValue: Integer): Boolean;
+begin
+  Result := True;
+  if ACurrentIndex + 1 = GetCardinality then
+    AStartIndexValue := FConditionRecord.Validation.Count
+  else if ACurrentIndex > 0 then
+    AStartIndexValue := Max(ACurrentIndexArray[ACurrentIndex - 1], FConditionRecord.MinIndices[ACurrentIndex])
+  else
+    AStartIndexValue := FConditionRecord.MinIndices[ACurrentIndex];
+end;
+
+function TValidationsToBlockAssignments.ValidateIndexValue(constref ACurrentIndexArray: TIndexArray;
+  const ACurrentIndex: Integer): TIndexValidationResult;
+var
+  start: Integer;
+begin
+  if ACurrentIndexArray[ACurrentIndex] > FConditionRecord.Validation.Count then
+    Result := ivrBacktrack
+  else begin
+    if ACurrentIndex > 0 then
+      start := ACurrentIndexArray[ACurrentIndex - 1]
+    else
+      start := 0;
+
+    if FConditionRecord.ValidationLengths[start, ACurrentIndexArray[ACurrentIndex]]
+        <= Length(FConditionRecord.Blocks[ACurrentIndex].Pattern) then
+      Result := ivrValid
+    else
+      Result := ivrBacktrack;
+  end;
+
+  Result := UpdateCombinations(Result, ACurrentIndexArray, ACurrentIndex);
+end;
+
+{ TDamageToValidationAssignments }
+
+function TDamageToValidationAssignments.CalcValidationSpan(constref ACurrentIndexArray: TIndexArray;
+  const ALastDamageIndex, AValidationNumber: Integer): Integer;
+var
+  spanStart: Integer;
+begin
+  spanStart := ALastDamageIndex;
+  while (spanStart > 0) and (ACurrentIndexArray[spanStart - 1] = AValidationNumber) do
+    Dec(spanStart);
+  Result := FBlock.Damages[ALastDamageIndex].Length;
+  if spanStart < ALastDamageIndex then
+    Inc(Result, FBlock.Damages[ALastDamageIndex].Start - FBlock.Damages[spanStart].Start);
+end;
+
+constructor TDamageToValidationAssignments.Create(constref AConditionRecord: TConditionRecord; constref ABlock: TBlock;
+  const AStartValidationIndex, AStopValidationIndex: Integer);
+begin
+  FConditionRecord := AConditionRecord;
+  FBlock := ABlock;
+  FValidationStartIndex := AStartValidationIndex;
+  FValidationStopIndex := AStopValidationIndex;
+end;
+
+function TDamageToValidationAssignments.GetCardinality: Integer;
+begin
+  Result := FBlock.Damages.Count;
+end;
+
+function TDamageToValidationAssignments.TryGetStartIndexValue(constref ACurrentIndexArray: TIndexArray;
+  const ACurrentIndex: Integer; out AStartIndexValue: Integer): Boolean;
+begin
+  Result := True;
+  if ACurrentIndex > 0 then
+    AStartIndexValue := ACurrentIndexArray[ACurrentIndex - 1]
+  else
+    AStartIndexValue := FValidationStartIndex;
+end;
+
+function TDamageToValidationAssignments.ValidateIndexValue(constref ACurrentIndexArray: TIndexArray;
+  const ACurrentIndex: Integer): TIndexValidationResult;
+var
+  i, prev: Integer;
+begin
+  i := ACurrentIndexArray[ACurrentIndex];
+  prev := ACurrentIndex - 1;
+  // Checks maximum index value.
+  if i > FValidationStopIndex then
+    Result := ivrBacktrack
+  // Checks if there is enough space after this damage for remaining validation numbers.
+  else if (i < FValidationStopIndex)
+  and (FConditionRecord.ValidationLengths[i + 1, FValidationStopIndex + 1] + 1 > FBlock.Damages[ACurrentIndex].CharsRemaining) then
+    Result := ivrSkip
+  // Checks if there is enough space before this damage for previous validation numbers.
+  else if (FValidationStartIndex < i)
+  and (FConditionRecord.ValidationLengths[FValidationStartIndex, i] + 1 >= FBlock.Damages[ACurrentIndex].Start) then
+    Result := ivrBacktrack
+  // Checks if there is enough space between previous and this damage for skipped validation numbers.
+  else if (ACurrentIndex > 0)
+  and (ACurrentIndexArray[prev] + 1 < i)
+  and (FConditionRecord.ValidationLengths[ACurrentIndexArray[prev] + 1, i] + 2
+      > FBlock.Damages[ACurrentIndex].Start - FBlock.Damages[prev].Start - FBlock.Damages[prev].Length) then
+    Result := ivrBacktrack
+  // Checks if span is small enough to fit within this validation number.
+  else if FConditionRecord.Validation[i] < CalcValidationSpan(ACurrentIndexArray, ACurrentIndex, i) then
+    Result := ivrSkip
+  else
+    Result := ivrValid;
+end;
+
+{ TValidationPositionOffsets }
+
+function TValidationPositionOffsets.CalcCombinations(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex:
+  Integer): Int64;
+var
+  space, start, stop: Integer;
+begin
+  stop := FPositionInfos[ACurrentIndex].ValidationIndex - 1;
+  if ACurrentIndex > 0 then
+  begin
+    space := ACurrentIndexArray[ACurrentIndex] - ACurrentIndexArray[ACurrentIndex - 1]
+      - FConditionRecord.Validation[FPositionInfos[ACurrentIndex - 1].ValidationIndex] - 2;
+    start := FPositionInfos[ACurrentIndex - 1].ValidationIndex + 1;
+    Result :=  FConditionRecord.CalcCombinationsWildcardSequence(space, start, stop);
+  end
+  else begin
+    // Handles first calculated offset.
+    space := ACurrentIndexArray[0] - 2;
+    Result := FConditionRecord.CalcCombinationsWildcardSequence(space, FValidationStartIndex, stop);
+  end;
+
+  if (Result > 0) and (ACurrentIndex + 1 = GetCardinality) then
+  begin
+    // Handles last calculated offset.
+    space := FBlockLength - ACurrentIndexArray[ACurrentIndex] - FConditionRecord.Validation[FPositionInfos.Last.ValidationIndex];
+    start := FPositionInfos.Last.ValidationIndex + 1;
+    Result := Result * FConditionRecord.CalcCombinationsWildcardSequence(space, start, FValidationStopIndex);
+  end;
+end;
+
+constructor TValidationPositionOffsets.Create(constref AConditionRecord: TConditionRecord; constref APositionInfos:
+  TValidationPositionInfos; const ABlockLength, AValidationStartIndex, AValidationStopIndex: Integer);
+begin
+  FConditionRecord := AConditionRecord;
+  FPositionInfos := APositionInfos;
+  FBlockLength := ABlockLength;
+  FValidationStartIndex := AValidationStartIndex;
+  FValidationStopIndex := AValidationStopIndex;
+  inherited Create;
+end;
+
+function TValidationPositionOffsets.GetCardinality: Integer;
+begin
+  Result := FPositionInfos.Count;
+end;
+
+function TValidationPositionOffsets.TryGetStartIndexValue(constref ACurrentIndexArray: TIndexArray;
+  const ACurrentIndex: Integer; out AStartIndexValue: Integer): Boolean;
+var
+  info: TValidationPositionInfo;
+begin
+  info := FPositionInfos[ACurrentIndex];
+  AStartIndexValue := info.MinStart;
+  // Adjusts start value to avoid overlap of this validation number with the previous one (the one from previous
+  // position info).
+  if ACurrentIndex > 0 then
+    AStartIndexValue := Max(AStartIndexValue,
+      ACurrentIndexArray[ACurrentIndex - 1] + FConditionRecord.Validation[FPositionInfos[ACurrentIndex - 1].ValidationIndex] + 1);
+  Result := True;
+end;
+
+function TValidationPositionOffsets.ValidateIndexValue(constref ACurrentIndexArray: TIndexArray; const ACurrentIndex:
+  Integer): TIndexValidationResult;
+begin
+  if ACurrentIndexArray[ACurrentIndex] <= FPositionInfos[ACurrentIndex].MaxStart then
+    Result := ivrValid
+  else
+    Result := ivrBacktrack;
+
+  Result := UpdateCombinations(Result, ACurrentIndexArray, ACurrentIndex);
+end;
+
+{ TConditionRecord }
+
+procedure TConditionRecord.InitValidationLengths;
+var
+  i, j: Integer;
+begin
+  SetLength(FValidationLengths, FValidation.Count + 1, FValidation.Count + 1);
+  for i := 0 to FValidation.Count do
+  begin
+    FValidationLengths[i, i] := 0;
+    for j := i + 1 to FValidation.Count do
+      if FValidationLengths[i, j - 1] <> 0 then
+        FValidationLengths[i, j] := FValidationLengths[i, j - 1] + FValidation[j - 1] + 1
+      else
+        FValidationLengths[i, j] := FValidationLengths[i, j - 1] + FValidation[j - 1]
+  end;
+end;
+
+procedure TConditionRecord.InitMinIndices;
+var
+  i, j, patternsLength: Integer;
+begin
+  SetLength(FMinIndices, FBlocks.Count - 1);
+  patternsLength := Length(FBlocks[FBlocks.Count - 1].Pattern);
+  j := FValidation.Count;
+  for i := FBlocks.Count - 2 downto 0 do
+  begin
+    while (j >= 0) and (FValidationLengths[j, FValidation.Count] <= patternsLength) do
+      Dec(j);
+    FMinIndices[i] := j + 1;
+    patternsLength := patternsLength + 1 + Length(FBlocks[i].Pattern);
+  end;
+end;
+
+function TConditionRecord.CalcCombinationsBlockSingleValidation(constref ABlock: TBlock; const AIndex: Integer): Int64;
+var
+  len, combinedDamagesLength: Integer;
+begin
+  len := Length(ABlock.Pattern);
+  if len < FValidation[AIndex] then
+    Result := 0
+  else if ABlock.Damages.Count = 0 then
+    Result := len - FValidation[AIndex] + 1
+  else begin
+    combinedDamagesLength := ABlock.Damages.Last.Start + ABlock.Damages.Last.Length - ABlock.Damages.First.Start;
+    if FValidation[AIndex] < combinedDamagesLength then
+      Result := 0
+    else begin
+      Result := Min(Min(Min(
+        ABlock.Damages.First.Start,
+        FValidation[AIndex] - combinedDamagesLength + 1),
+        len - FValidation[AIndex] + 1),
+        ABlock.Damages.Last.CharsRemaining + 1);
+    end;
+  end;
+end;
+
+function TConditionRecord.CalcCombinationsBlockMultiValidations(constref ABlock: TBlock; constref AIndices:
+  TIndexArray; const AStartIndex, AStopIndex: Integer): Int64;
+var
+  i, high: Integer;
+  position: TValidationPositionInfo;
+  positions: TValidationPositionInfos;
+  validationPositionOffsets: TValidationPositionOffsets;
+  offsets: TIndexArray;
+begin
+  positions := TValidationPositionInfos.Create;
+  high := Length(AIndices) - 1;
+  // Initializes first info record.
+  position.ValidationIndex := AIndices[0];
+  position.MaxStart := ABlock.Damages[0].Start;
+  position.MinStart := 1;
+  for i := 1 to high do
+    if AIndices[i] <> position.ValidationIndex then
+    begin
+      // Finalizes current info record.
+      position.MaxStart := Min(position.MaxStart, ABlock.Damages[i].Start - 1 - FValidation[position.ValidationIndex]);
+      position.MinStart := Max(position.MinStart,
+        ABlock.Damages[i - 1].Start + ABlock.Damages[i - 1].Length - FValidation[position.ValidationIndex]);
+      positions.Add(position);
+      // Initializes next info record.
+      position.ValidationIndex := AIndices[i];
+      position.MaxStart := ABlock.Damages[i].Start;
+      position.MinStart := position.MinStart + FValidationLengths[AIndices[i - 1], AIndices[i]] + 1;
+    end;
+  // Finalizes last info record.
+  position.MaxStart := Min(position.MaxStart, Length(ABlock.Pattern) + 1 - FValidation[position.ValidationIndex]);
+  position.MinStart := Max(position.MinStart,
+    ABlock.Damages[high].Start + ABlock.Damages[high].Length - FValidation[position.ValidationIndex]);
+  positions.Add(position);
+
+  Result := 0;
+  validationPositionOffsets := TValidationPositionOffsets.Create(Self, positions, Length(ABlock.Pattern),
+    AStartIndex, AStopIndex);
+  for offsets in validationPositionOffsets do
+    Result := Result + validationPositionOffsets.GetCombinations;
+  validationPositionOffsets.Free;
+
+  positions.Free;
+end;
+
+function TConditionRecord.CalcValidationsId(const AStartIndex, AStopIndex: Integer): Int64;
+var
+  i: Integer;
+begin
+  // Requires 'FValidations[i] < 32' for each 'i' and 'AStopIndex - AStartIndex < 12'.
+  Result := FValidation[AStartIndex];
+  for i := AStartIndex + 1 to AStopIndex do
+    Result := (Result shl 5) or FValidation[i];
+end;
+
+constructor TConditionRecord.Create(constref ACombinationsCache: TCombinationsCache);
+begin
+  FBlocks := TBlocks.Create;
+  FValidation := TIntegerList.Create;
+  FCombinationsCache := ACombinationsCache;
+end;
+
+destructor TConditionRecord.Destroy;
+begin
+  FBlocks.Free;
+  FValidation.Free;
+  inherited Destroy;
+end;
+
+procedure TConditionRecord.AddBlocks(const APattern: string);
+var
+  split: TStringArray;
+  part: string;
+  blockCache: TBlockCombinationsCache;
+begin
+  split := APattern.Split([COperationalChar]);
+  for part in split do
+    if Length(part) > 0 then
+    begin
+      if not FCombinationsCache.TryGetValue(part, blockCache) then
+      begin
+        blockCache := TBlockCombinationsCache.Create;
+        FCombinationsCache.Add(part, blockCache);
+      end;
+      FBlocks.Add(TBlock.Create(part, blockCache));
+    end;
+end;
+
+function TConditionRecord.GenerateBlockAssignments: Int64;
+var
+  validationsToBlockAssignments: TValidationsToBlockAssignments;
+  indices: TIndexArray;
+begin
+  InitValidationLengths;
+  InitMinIndices;
+
+  Result := 0;
+  validationsToBlockAssignments := TValidationsToBlockAssignments.Create(Self);
+  for indices in validationsToBlockAssignments do
+    Result := Result + validationsToBlockAssignments.GetCombinations;
+  validationsToBlockAssignments.Free;
+end;
+
+function TConditionRecord.CalcCombinationsBlock(constref ABlock: TBlock; const AStartIndex, AStopIndex: Integer): Int64;
+var
+  validationsId: Int64;
+  indices: TIndexArray;
+  damageToValidationAssignments: TDamageToValidationAssignments;
+begin
+  // No validation number assigned to this block.
+  if AStartIndex > AStopIndex then
+  begin
+    if ABlock.Damages.Count = 0 then
+      Result := 1
+    else
+      Result := 0;
+  end
+  // One validation number assigned to this block.
+  else if AStartIndex = AStopIndex then
+    Result := CalcCombinationsBlockSingleValidation(ABlock, AStartIndex)
+  // Multiple validation numbers assigned to this block. Checks cache first.
+  else begin
+    validationsId := CalcValidationsId(AStartIndex, AStopIndex);
+    if not ABlock.CombinationsCache.TryGetValue(validationsId, Result) then
+    begin
+      Result := 0;
+
+      // Assigns validation numbers to specific damages.
+      damageToValidationAssignments := TDamageToValidationAssignments.Create(Self, ABlock, AStartIndex, AStopIndex);
+      for indices in damageToValidationAssignments do
+        Result := Result + CalcCombinationsBlockMultiValidations(ABlock, indices, AStartIndex, AStopIndex);
+      damageToValidationAssignments.Free;
+
+      ABlock.CombinationsCache.Add(validationsId, Result);
+    end;
+  end;
+end;
+
+function TConditionRecord.CalcCombinationsWildcardSequence(const ASequenceLength, AStartIndex, AStopIndex: Integer):
+  Int64;
+var
+  count, freedoms: Integer;
+begin
+  if AStartIndex < AStopIndex + 1 then
+  begin
+    count := AStopIndex + 1 - AStartIndex;
+    freedoms := ASequenceLength - FValidationLengths[AStartIndex, AStopIndex + 1];
+    if freedoms >= 0 then
+      Result := BinomialCoefficients.Get(count + freedoms, freedoms)
+    else
+      Result := 0;
+  end
+  else
+    Result := 1;
+end;
+
+{ THotSprings }
+
 constructor THotSprings.Create;
 begin
-  FValidation := specialize TList<Integer>.Create;
+  FCombinationsCache := TCombinationsCache.Create([doOwnsValues]);
 end;
 
 destructor THotSprings.Destroy;
 begin
-  FValidation.Free;
+  FCombinationsCache.Free;
   inherited Destroy;
 end;
 
 procedure THotSprings.ProcessDataLine(const ALine: string);
 var
-  split: TStringArray;
+  conditionRecord1, conditionRecord2: TConditionRecord;
-  i, val, maxFreeOperationalCount: Integer;
+  mainSplit, split: TStringArray;
+  part, unfolded: string;
+  i: Integer;
 begin
-  FValidation.Clear;
+  conditionRecord1 := TConditionRecord.Create(FCombinationsCache);
-  split := ALine.Split([' ', ',']);
+  conditionRecord2 := TConditionRecord.Create(FCombinationsCache);
-  FSpringPattern := split[0];
 
-  maxFreeOperationalCount := Length(FSpringPattern) - Length(split) + 2;
+  mainSplit := ALine.Split([' ']);
-  for i := 1 to Length(split) - 1 do
-  begin
-    val := StrToInt(split[i]);
-    FValidation.Add(val);
-    Dec(maxFreeOperationalCount, val);
-  end;
 
-  ExtendArrangement('', maxFreeOperationalCount, 0);
+  // Adds blocks for part 1.
+  conditionRecord1.AddBlocks(mainSplit[0]);
+
+  // Adds blocks for part 2.
+  unfolded := mainSplit[0];
+  for i := 2 to CPart2Repetition do
+    unfolded := unfolded + CWildcardChar + mainSplit[0];
+  conditionRecord2.AddBlocks(unfolded);
+
+  // Adds validation numbers.
+  split := mainSplit[1].Split([',']);
+  for part in split do
+    conditionRecord1.Validation.Add(StrToInt(part));
+  for i := 1 to CPart2Repetition do
+    conditionRecord2.Validation.AddRange(conditionRecord1.Validation);
+
+  FPart1 := FPart1 + conditionRecord1.GenerateBlockAssignments;
+  FPart2 := FPart2 + conditionRecord2.GenerateBlockAssignments;
+
+  conditionRecord1.Free;
+  conditionRecord2.Free;
 end;
 
 procedure THotSprings.Finish;

tests/AdventOfCodeFPCUnit.lpi

@@ -152,6 +152,10 @@
         <Filename Value="USnowverloadTestCases.pas"/>
         <IsPartOfProject Value="True"/>
       </Unit>
+      <Unit>
+        <Filename Value="UBinomialCoefficientsTestCases.pas"/>
+        <IsPartOfProject Value="True"/>
+      </Unit>
     </Units>
   </ProjectOptions>
   <CompilerOptions>

tests/AdventOfCodeFPCUnit.lpr

@@ -10,7 +10,7 @@ uses
   UFloorWillBeLavaTestCases, UClumsyCrucibleTestCases, ULavaductLagoonTestCases, UAplentyTestCases,
   UPulsePropagationTestCases, UStepCounterTestCases, USandSlabsTestCases, ULongWalkTestCases,
   UNeverTellMeTheOddsTestCases, USnowverloadTestCases, UBigIntTestCases, UPolynomialTestCases,
-  UPolynomialRootsTestCases;
+  UPolynomialRootsTestCases, UBinomialCoefficientsTestCases;
 
 {$R *.res}
 

tests/UBinomialCoefficientsTestCases.pas

@@ -0,0 +1,138 @@
+{
+  Solutions to the Advent Of Code.
+  Copyright (C) 2024  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 <http://www.gnu.org/licenses/>.
+}
+
+unit UBinomialCoefficientsTestCases;
+
+{$mode ObjFPC}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils, fpcunit, testregistry, UBinomialCoefficients;
+
+type
+
+  { TBinomialCoefficientsTestCase }
+
+  TBinomialCoefficientsTestCase = class(TTestCase)
+  private
+    FBinomialCoefficientCache: TBinomialCoefficientCache;
+    procedure RunRangeError;
+    procedure AssertEqualsCalculation(const AN, AK, AExpected: Cardinal);
+    procedure AssertEqualsCachedRowsCount(const AExpected: Cardinal);
+  protected
+    procedure SetUp; override;
+    procedure TearDown; override;
+  published
+    procedure TestZeroChooseZero;
+    procedure TestNChooseZero;
+    procedure TestNChooseN;
+    procedure TestNChooseK;
+    procedure TestCombined;
+    procedure TestFullRow;
+    procedure TestRangeError;
+  end;
+
+implementation
+
+{ TBinomialCoefficientsTestCase }
+
+procedure TBinomialCoefficientsTestCase.RunRangeError;
+begin
+  FBinomialCoefficientCache.Get(1, 5);
+end;
+
+procedure TBinomialCoefficientsTestCase.AssertEqualsCalculation(const AN, AK, AExpected: Cardinal);
+begin
+  AssertEquals('Unexpected calculation result', AExpected, FBinomialCoefficientCache.Get(AN, AK));
+end;
+
+procedure TBinomialCoefficientsTestCase.AssertEqualsCachedRowsCount(const AExpected: Cardinal);
+begin
+  AssertEquals('Unexpected cached rows count', AExpected, FBinomialCoefficientCache.GetCachedRowsCount);
+end;
+
+procedure TBinomialCoefficientsTestCase.SetUp;
+begin
+  FBinomialCoefficientCache := TBinomialCoefficientCache.Create;
+end;
+
+procedure TBinomialCoefficientsTestCase.TearDown;
+begin
+  FBinomialCoefficientCache.Free;
+end;
+
+procedure TBinomialCoefficientsTestCase.TestZeroChooseZero;
+begin
+  AssertEqualsCalculation(0, 0, 1);
+  AssertEqualsCachedRowsCount(1);
+end;
+
+procedure TBinomialCoefficientsTestCase.TestNChooseZero;
+begin
+  AssertEqualsCalculation(15, 0, 1);
+  AssertEqualsCachedRowsCount(16);
+end;
+
+procedure TBinomialCoefficientsTestCase.TestNChooseN;
+begin
+  AssertEqualsCalculation(11, 11, 1);
+  AssertEqualsCachedRowsCount(12);
+end;
+
+procedure TBinomialCoefficientsTestCase.TestNChooseK;
+begin
+  AssertEqualsCalculation(8, 3, 56);
+  AssertEqualsCachedRowsCount(9);
+end;
+
+procedure TBinomialCoefficientsTestCase.TestCombined;
+begin
+  AssertEqualsCalculation(5, 1, 5);
+  AssertEqualsCachedRowsCount(6);
+  AssertEqualsCalculation(8, 4, 70);
+  AssertEqualsCachedRowsCount(9);
+  AssertEqualsCalculation(3, 1, 3);
+  AssertEqualsCachedRowsCount(9);
+end;
+
+procedure TBinomialCoefficientsTestCase.TestFullRow;
+begin
+  AssertEqualsCalculation(5, 0, 1);
+  AssertEqualsCachedRowsCount(6);
+  AssertEqualsCalculation(5, 1, 5);
+  AssertEqualsCachedRowsCount(6);
+  AssertEqualsCalculation(5, 2, 10);
+  AssertEqualsCachedRowsCount(6);
+  AssertEqualsCalculation(5, 3, 10);
+  AssertEqualsCachedRowsCount(6);
+  AssertEqualsCalculation(5, 4, 5);
+  AssertEqualsCachedRowsCount(6);
+  AssertEqualsCalculation(5, 5, 1);
+  AssertEqualsCachedRowsCount(6);
+end;
+
+procedure TBinomialCoefficientsTestCase.TestRangeError;
+begin
+  AssertException(ERangeError, @RunRangeError);
+end;
+
+initialization
+
+  RegisterTest('Helper', TBinomialCoefficientsTestCase);
+end.
+

tests/UHotSpringsTestCases.pas

@@ -33,6 +33,7 @@ type
     function CreateSolver: ISolver; override;
   published
     procedure TestPart1;
+    procedure TestPart2;
   end;
 
   { THotSpringsTestCase }
@@ -40,14 +41,20 @@ type
   THotSpringsTestCase = class(TSolverTestCase)
   protected
     function CreateSolver: ISolver; override;
-    procedure TestSingleLine(const ALine: string; const AValue: Integer);
+    procedure TestSingleLine(const ALine: string);
   published
-    procedure TestExampleLine1;
+    procedure TestExampleLine1Part1;
-    procedure TestExampleLine2;
+    procedure TestExampleLine2Part1;
-    procedure TestExampleLine3;
+    procedure TestExampleLine3Part1;
-    procedure TestExampleLine4;
+    procedure TestExampleLine4Part1;
-    procedure TestExampleLine5;
+    procedure TestExampleLine5Part1;
-    procedure TestExampleLine6;
+    procedure TestExampleLine6Part1;
+    procedure TestExampleLine1Part2;
+    procedure TestExampleLine2Part2;
+    procedure TestExampleLine3Part2;
+    procedure TestExampleLine4Part2;
+    procedure TestExampleLine5Part2;
+    procedure TestExampleLine6Part2;
   end;
 
 implementation
@@ -64,6 +71,11 @@ begin
   AssertEquals(21, FSolver.GetResultPart1);
 end;
 
+procedure THotSpringsExampleTestCase.TestPart2;
+begin
+  AssertEquals(525152, FSolver.GetResultPart2);
+end;
+
 { THotSpringsTestCase }
 
 function THotSpringsTestCase.CreateSolver: ISolver;
@@ -71,42 +83,83 @@ begin
   Result := THotSprings.Create;
 end;
 
-procedure THotSpringsTestCase.TestSingleLine(const ALine: string; const AValue: Integer);
+procedure THotSpringsTestCase.TestSingleLine(const ALine: string);
 begin
   FSolver.Init;
   FSolver.ProcessDataLine(ALine);
   FSolver.Finish;
-  AssertEquals(AValue, FSolver.GetResultPart1);
 end;
 
-procedure THotSpringsTestCase.TestExampleLine1;
+procedure THotSpringsTestCase.TestExampleLine1Part1;
 begin
-  TestSingleLine('???.### 1,1,3', 1);
+  TestSingleLine('???.### 1,1,3');
+  AssertEquals(1, FSolver.GetResultPart1);
 end;
 
-procedure THotSpringsTestCase.TestExampleLine2;
+procedure THotSpringsTestCase.TestExampleLine2Part1;
 begin
-  TestSingleLine('.??..??...?##. 1,1,3', 4);
+  TestSingleLine('.??..??...?##. 1,1,3');
+  AssertEquals(4, FSolver.GetResultPart1);
 end;
 
-procedure THotSpringsTestCase.TestExampleLine3;
+procedure THotSpringsTestCase.TestExampleLine3Part1;
 begin
-  TestSingleLine('?#?#?#?#?#?#?#? 1,3,1,6', 1);
+  TestSingleLine('?#?#?#?#?#?#?#? 1,3,1,6');
+  AssertEquals(1, FSolver.GetResultPart1);
 end;
 
-procedure THotSpringsTestCase.TestExampleLine4;
+procedure THotSpringsTestCase.TestExampleLine4Part1;
 begin
-  TestSingleLine('????.#...#... 4,1,1', 1);
+  TestSingleLine('????.#...#... 4,1,1');
+  AssertEquals(1, FSolver.GetResultPart1);
 end;
 
-procedure THotSpringsTestCase.TestExampleLine5;
+procedure THotSpringsTestCase.TestExampleLine5Part1;
 begin
-  TestSingleLine('????.######..#####. 1,6,5', 4);
+  TestSingleLine('????.######..#####. 1,6,5');
+  AssertEquals(4, FSolver.GetResultPart1);
 end;
 
-procedure THotSpringsTestCase.TestExampleLine6;
+procedure THotSpringsTestCase.TestExampleLine6Part1;
 begin
-  TestSingleLine('?###???????? 3,2,1', 10);
+  TestSingleLine('?###???????? 3,2,1');
+  AssertEquals(10, FSolver.GetResultPart1);
+end;
+
+procedure THotSpringsTestCase.TestExampleLine1Part2;
+begin
+  TestSingleLine('???.### 1,1,3');
+  AssertEquals(1, FSolver.GetResultPart2);
+end;
+
+procedure THotSpringsTestCase.TestExampleLine2Part2;
+begin
+  TestSingleLine('.??..??...?##. 1,1,3');
+  AssertEquals(16384, FSolver.GetResultPart2);
+end;
+
+procedure THotSpringsTestCase.TestExampleLine3Part2;
+begin
+  TestSingleLine('?#?#?#?#?#?#?#? 1,3,1,6');
+  AssertEquals(1, FSolver.GetResultPart2);
+end;
+
+procedure THotSpringsTestCase.TestExampleLine4Part2;
+begin
+  TestSingleLine('????.#...#... 4,1,1');
+  AssertEquals(16, FSolver.GetResultPart2);
+end;
+
+procedure THotSpringsTestCase.TestExampleLine5Part2;
+begin
+  TestSingleLine('????.######..#####. 1,6,5');
+  AssertEquals(2500, FSolver.GetResultPart2);
+end;
+
+procedure THotSpringsTestCase.TestExampleLine6Part2;
+begin
+  TestSingleLine('?###???????? 3,2,1');
+  AssertEquals(506250, FSolver.GetResultPart2);
 end;
 
 initialization