Added solution for "Day 5: If You Give A Seed A Fertilizer", part 2

UGiveSeedFertilizer.pas

@@ -18,30 +18,41 @@
 unit UGiveSeedFertilizer;
 
 {$mode ObjFPC}{$H+}
+{$modeswitch AdvancedRecords+}
 
 interface
 
 uses
-  Classes, SysUtils, fgl, USolver;
+  Classes, SysUtils, fgl, Math, USolver;
 
 type
 
+  { TValueRange }
+
+  TValueRange = record
+    Part: Integer;
+    Start, Length: Cardinal;
+    class operator = (Left, Right : TValueRange): Boolean;
+  end;
+
+  TValueRanges = specialize TFPGList<TValueRange>;
+
   { TAlmanacMapRange }
 
   TAlmanacMapRange = class
   private
-    FDestinationStart, FSourceStart, FSourceEnd, FDifference1, FDifference2: Cardinal;
+    FDestinationStart, FSourceStart, FSourceLast, FLength, FDifference1, FDifference2: Cardinal;
   public
     constructor Create(const ALine: string);
     constructor Create(const ADestinationStart, ASourceStart, ALength: Cardinal);
-    function TryConvert(const AInput: Cardinal; out OOutput: Cardinal): Boolean;
+    procedure TryConvert(const AInput: TValueRange; const AUnconverted, AConverted: TValueRanges);
   end;
 
   { TGiveSeedFertilizer }
 
   TGiveSeedFertilizer = class(TSolver)
   private
-    FNew, FConverted, FProcessedIndices: specialize TFPGList<Cardinal>;
+    FNew, FUnconverted, FConverted: TValueRanges;
     procedure ProcessSeeds(const ALine: string);
     procedure ProcessMapRange(const ALine: string);
     procedure FinishMap;
@@ -56,6 +67,13 @@ type
 
 implementation
 
+{ TValueRange }
+
+class operator TValueRange. = (Left, Right: TValueRange): Boolean;
+begin
+  Result := (Left.Part = Right.Part) and (Left.Start = Right.Start) and (Left.Length = Right.Length);
+end;
+
 { TAlmanacMapRange }
 
 constructor TAlmanacMapRange.Create(const ALine: string);
@@ -70,12 +88,13 @@ constructor TAlmanacMapRange.Create(const ADestinationStart, ASourceStart, ALeng
 begin
   FDestinationStart := ADestinationStart;
   FSourceStart := ASourceStart;
+  FLength := ALength;
 
-  // All input values are within Cardinal range, but the calculations might not be.
+  // All input values are within Cardinal range, but the calculation results might not be.
-  if ASourceStart <= Cardinal.MaxValue - ALength then
+  if ASourceStart <= Cardinal.MaxValue - ALength + 1 then
-    FSourceEnd := ASourceStart + ALength
+    FSourceLast := ASourceStart + ALength - 1
   else
-    FSourceEnd := Cardinal.MaxValue;
+    FSourceLast := Cardinal.MaxValue;
 
   if ADestinationStart >= ASourceStart then
   begin
@@ -88,19 +107,44 @@ begin
   end;
 end;
 
-function TAlmanacMapRange.TryConvert(const AInput: Cardinal; out OOutput: Cardinal): Boolean;
+procedure TAlmanacMapRange.TryConvert(const AInput: TValueRange; const AUnconverted, AConverted: TValueRanges);
+var
+  inputLast: Cardinal;
+  splitValue: TValueRange;
 begin
-  if (FSourceStart <= AInput) and (AInput < FSourceEnd) then
+  if AInput.Start <= Cardinal.MaxValue - AInput.Length + 1 then
-  begin
+    inputLast := AInput.Start + AInput.Length - 1
-    if FDifference1 > 0 then
-      OOutput := AInput + FDifference1
   else
-      OOutput := AInput - FDifference2;
+    inputLast := Cardinal.MaxValue;
-    Result := True;
+
-  end
+  splitValue.Part := AInput.Part;
-  else begin
+
-    OOutput := 0;
+  // Converts the convertible part of the value range, if any.
-    Result := False;
+  if Min(FSourceLast, inputLast) >= Max(FSourceStart, AInput.Start) then
+  begin
+    splitValue.Start := Max(FSourceStart, AInput.Start);
+    splitValue.Length := Min(FSourceLast, inputLast) - splitValue.Start + 1;
+    if FDifference1 > 0 then
+      Inc(splitValue.Start, FDifference1)
+    else
+      Dec(splitValue.Start, FDifference2);
+    AConverted.Add(splitValue);
+  end;
+
+  // Splits off the part before the convertible part, if any.
+  if FSourceStart > AInput.Start then
+  begin
+    splitValue.Start := AInput.Start;
+    splitValue.Length := Min(FSourceStart - AInput.Start, AInput.Length);
+    AUnconverted.Add(splitValue);
+  end;
+
+  // Splits off the part after the convertible part, if any.
+  if inputLast > FSourceLast then
+  begin
+    splitValue.Start := Max(FSourceLast + 1, AInput.Start);
+    splitValue.Length := Min(inputLast - FSourceLast, AInput.Length);
+    AUnconverted.Add(splitValue);
   end;
 end;
 
@@ -110,43 +154,51 @@ procedure TGiveSeedFertilizer.ProcessSeeds(const ALine: string);
 var
   split: TStringArray;
   i: Integer;
+  value: TValueRange;
 begin
   split := Aline.Split(' ');
-  for i := 1 to Length(split) - 1 do
+  for i := 1 to Length(split) div 2 do
   begin
-    FNew.Add(StrToDWord(split[i]));
+    // Adds values for part 1.
+    value.Part := 1;
+    value.Length := 1;
+    value.Start := StrToDWord(split[2 * i - 1]);
+    FNew.Add(value);
+    value.Start := StrToDWord(split[2 * i]);
+    FNew.Add(value);
+
+    // Adds values for part 2.
+    value.Part := 2;
+    value.Start := StrToDWord(split[2 * i - 1]);
+    value.Length := StrToDWord(split[2 * i]);
+    FNew.Add(value);
   end;
 end;
 
 procedure TGiveSeedFertilizer.ProcessMapRange(const ALine: string);
 var
   range: TAlmanacMapRange;
-  i: Integer;
+  value: TValueRange;
-  converted: Cardinal;
+  temp: TValueRanges;
 begin
-  // Converts all "new" values that fall into this mapping range.
+  // Tries to convert all value ranges that have not yet been converted by the current map.
   range := TAlmanacMapRange.Create(ALine);
-  for i := 0 to FNew.Count - 1 do
+  for value in FNew do
   begin
-    if range.TryConvert(FNew[i], converted) then
+    range.TryConvert(value, FUnconverted, FConverted);
-    begin
-      FConverted.Add(converted);
-      FProcessedIndices.Add(i);
-    end;
   end;
   range.Free;
 
-  // Forgets the converted values.
+  // Discards all new and moves unconverted back as new.
-  for i := FProcessedIndices.Count - 1 downto 0 do
+  FNew.Clear;
-  begin
+  temp := FNew;
-    FNew.Delete(FProcessedIndices[i]);
+  FNew := FUnconverted;
-  end;
+  FUnconverted := temp;
-  FProcessedIndices.Clear;
 end;
 
 procedure TGiveSeedFertilizer.FinishMap;
 var
-  value: Cardinal;
+  value: TValueRange;
 begin
   // Resets the lists for the next map, remaining values stay unconverted.
   for value in FConverted do
@@ -158,16 +210,16 @@ end;
 
 constructor TGiveSeedFertilizer.Create;
 begin
-  FNew := specialize TFPGList<Cardinal>.Create;
+  FNew := TValueRanges.Create;
-  FConverted := specialize TFPGList<Cardinal>.Create;
+  FUnconverted := TValueRanges.Create;
-  FProcessedIndices := specialize TFPGList<Cardinal>.Create;
+  FConverted := TValueRanges.Create;
 end;
 
 destructor TGiveSeedFertilizer.Destroy;
 begin
   FNew.Free;
+  FUnconverted.Free;
   FConverted.Free;
-  FProcessedIndices.Free;
   inherited Destroy;
 end;
 
@@ -183,13 +235,20 @@ end;
 
 procedure TGiveSeedFertilizer.Finish;
 var
-  value: Cardinal;
+  value: TValueRange;
 begin
   FinishMap;
   for value in FNew do
   begin
-    if (FPart1 = 0) or (value < FPart1) then
+    if value.Part = 1 then
-      FPart1 := value;
+    begin
+      if (FPart1 = 0) or (value.Start < FPart1) then
+        FPart1 := value.Start;
+    end
+    else begin
+      if (FPart2 = 0) or (value.Start < FPart2) then
+        FPart2 := value.Start;
+    end;
   end;
 end;
 

tests/UGiveSeedFertilizerTestCases.pas

@@ -62,7 +62,7 @@ end;
 
 procedure TGiveSeedFertilizerFullDataTestCase.TestPart2;
 begin
-  AssertEquals(-1, FSolver.GetResultPart2);
+  AssertEquals(99751240, FSolver.GetResultPart2);
 end;
 
 { TGiveSeedFertilizerExampleTestCase }
@@ -79,7 +79,7 @@ end;
 
 procedure TGiveSeedFertilizerExampleTestCase.TestPart2;
 begin
-  AssertEquals(-1, FSolver.GetResultPart2);
+  AssertEquals(46, FSolver.GetResultPart2);
 end;
 
 initialization