Added solution for "Day 1: Trebuchet?!", part 1

puzzles/utrebuchet.pas

@@ -0,0 +1,81 @@
+unit UTrebuchet;
+
+{$mode ObjFPC}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils;
+
+type
+
+  { TTrebuchet }
+
+  TTrebuchet = class(TObject)
+  private
+    FValue: Integer;
+    procedure RunSolution;
+    procedure ProcessDataLine(const ALine: string);
+  public
+    class procedure Solve; static;
+    constructor Create;
+  end;
+
+implementation
+
+{ TTrebuchet }
+
+procedure TTrebuchet.RunSolution;
+var
+  data: TextFile;
+  s: string;
+begin
+  AssignFile(data, ConcatPaths(['data', 'trebuchet_calibration_document.txt']));
+  try
+    reset(data);
+    while (not EOF(data)) do
+    begin
+      readln(data, s);
+      ProcessDataLine(s);
+    end;
+  finally
+    CloseFile(data)
+  end;
+  WriteLn(FValue);
+end;
+
+procedure TTrebuchet.ProcessDataLine(const ALine: string);
+var
+  c: Char;
+  first, last: Integer;
+begin
+  first := -1;
+  last := -1;
+  for c in ALine do
+  begin
+    if c in ['0'..'9'] then
+    begin
+      last := StrToInt(c);
+      if first < 0 then
+        first := last;
+    end;
+  end;
+  Inc(FValue, first * 10 + last);
+end;
+
+class procedure TTrebuchet.Solve;
+var
+  trebuchet: TTrebuchet;
+begin
+  WriteLn('--- Day 1: Trebuchet?! ---');
+  trebuchet := TTrebuchet.Create;
+  trebuchet.RunSolution;
+end;
+
+constructor TTrebuchet.Create;
+begin
+  FValue := 0;
+end;
+
+end.
+