From cc868a6c0aad0866f85152fa7d7a4d1db7d76363 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20M=C3=BCller?= <stefan.mueller@aksdb.de>
Date: Mon, 4 Dec 2023 21:59:39 +0100
Subject: [PATCH] Added solution for "Day 4: Scratchcards", part 2

---
 solvers/UScratchcards.pas        | 41 ++++++++++++++++++++++++++++++--
 tests/UScratchcardsTestCases.pas |  4 ++--
 2 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/solvers/UScratchcards.pas b/solvers/UScratchcards.pas
index ede0449..c22ddfa 100644
--- a/solvers/UScratchcards.pas
+++ b/solvers/UScratchcards.pas
@@ -22,7 +22,7 @@ unit UScratchcards;
 interface
 
 uses
-  Classes, SysUtils, USolver;
+  Classes, SysUtils, fgl, USolver;
 
 type
 
@@ -30,8 +30,11 @@ type
 
   TScratchcards = class(TSolver)
   private
+    FCardCopies: specialize TFPGList<Integer>;
     function GetNumber(const AString: string; const AIndex: Integer): Integer;
   public
+    constructor Create;
+    destructor Destroy; override;
     procedure ProcessDataLine(const ALine: string); override;
     procedure Finish; override;
     function GetDataFileName: string; override;
@@ -48,12 +51,33 @@ begin
   Result := StrToInt(Trim(Copy(AString, AIndex * 3 + 1, 3)))
 end;
 
+constructor TScratchcards.Create;
+begin
+  FCardCopies := specialize TFPGList<Integer>.Create;
+end;
+
+destructor TScratchcards.Destroy;
+begin
+  FCardCopies.Free;
+  inherited Destroy;
+end;
+
 procedure TScratchcards.ProcessDataLine(const ALine: string);
 var
   cardSplit: TStringArray;
   wins: array of Integer;
-  count, i, have, win, cardPoints: Integer;
+  count, i, have, win, cardPoints, cardMatches, cardCopies: Integer;
 begin
+  // Counts copies of this card.
+  if FCardCopies.Count > 0 then
+  begin
+    cardCopies := FCardCopies[0];
+    FCardCopies.Delete(0);
+  end
+  else
+    cardCopies := 1;
+  Inc(FPart2, cardCopies);
+
   cardSplit := ALine.Split([':', '|']);
 
   // Determines winning numbers.
@@ -66,6 +90,7 @@ begin
 
   // Checks have numbers against winning numbers.
   cardPoints := 0;
+  cardMatches := 0;
   count := cardSplit[2].Length div 3;
   for i := 0 to count - 1 do
   begin
@@ -78,12 +103,24 @@ begin
           cardPoints := 1
         else
           Inc(cardPoints, cardPoints);
+        Inc(cardMatches);
         Break;
       end;
     end;
   end;
 
   Inc(FPart1, cardPoints);
+
+  // Adds copies of following cards and deletes the current card count.
+  if FCardCopies.Capacity < cardMatches then
+    FCardCopies.Capacity := cardMatches;
+  for i := 0 to cardMatches - 1 do
+  begin
+    if FCardCopies.Count <= i then
+      FCardCopies.Add(cardCopies + 1)
+    else
+      FCardCopies[i] :=  FCardCopies[i] + cardCopies;
+  end;
 end;
 
 procedure TScratchcards.Finish;
diff --git a/tests/UScratchcardsTestCases.pas b/tests/UScratchcardsTestCases.pas
index 5f41315..1377c5e 100644
--- a/tests/UScratchcardsTestCases.pas
+++ b/tests/UScratchcardsTestCases.pas
@@ -78,7 +78,7 @@ end;
 
 procedure TScratchcardsFullDataTestCase.TestPart2;
 begin
-  AssertEquals(-1, FSolver.GetResultPart2);
+  AssertEquals(5539496, FSolver.GetResultPart2);
 end;
 
 { TScratchcardsExampleTestCase }
@@ -103,7 +103,7 @@ end;
 
 procedure TScratchcardsExampleTestCase.TestPart2;
 begin
-  AssertEquals(-1, FSolver.GetResultPart2);
+  AssertEquals(30, FSolver.GetResultPart2);
 end;
 
 initialization