Added polynomial degree and coefficients as public properties

UPolynomial.pas

@@ -32,7 +32,11 @@ type
   TBigIntPolynomial = object
   private
     FCoefficients: array of TBigInt;
+    function GetDegree: Integer;
+    function GetCoefficient(const AIndex: Integer): TBigInt;
   public
+    property Degree: Integer read GetDegree;
+    property Coefficient[const AIndex: Integer]: TBigInt read GetCoefficient;
     function CalcValueAt(const AX: Int64): TBigInt;
     function IsEqualTo(const AOther: TBigIntPolynomial): Boolean;
     class function Create(const ACoefficients: array of TBigInt): TBigIntPolynomial; static;
@@ -47,6 +51,16 @@ implementation
 
 { TBigIntPolynomial }
 
+function TBigIntPolynomial.GetDegree: Integer;
+begin
+  Result := Length(FCoefficients) - 1;
+end;
+
+function TBigIntPolynomial.GetCoefficient(const AIndex: Integer): TBigInt;
+begin
+  Result := FCoefficients[AIndex];
+end;
+
 function TBigIntPolynomial.CalcValueAt(const AX: Int64): TBigInt;
 var
   i: Integer;
@@ -78,16 +92,19 @@ class function TBigIntPolynomial.Create(const ACoefficients: array of TBigInt):
 var
   high, i: integer;
 begin
-  high := 1;
-  for i := Length(ACoefficients) - 1 downto 1 do
+  high := -1;
+  for i := Length(ACoefficients) - 1 downto 0 do
     if ACoefficients[i] <> 0 then
     begin
       high := i;
       Break;
     end;
-  SetLength(Result.FCoefficients, high + 1);
-  for i := 0 to high do
-    Result.FCoefficients[i] := ACoefficients[i];
+  if high >= 0 then
+  begin
+    SetLength(Result.FCoefficients, high + 1);
+    for i := 0 to high do
+      Result.FCoefficients[i] := ACoefficients[i];
+  end;
 end;
 
 { Operators }

tests/UPolynomialTestCases.pas

@@ -29,7 +29,13 @@ type
   { TBigIntPolynomialTestCase }
 
   TBigIntPolynomialTestCase = class(TTestCase)
+  private
+    procedure TestCreateWithDegree(const ACoefficients: array of TBigInt; const ADegree: Integer);
   published
+    procedure TestCreate;
+    procedure TestCreateDegreeOne;
+    procedure TestCreateDegreeZero;
+    procedure TestCreateDegreeZeroTrim;
     procedure TestEqual;
     procedure TestUnequalSameLength;
     procedure TestUnequalDifferentLength;
@@ -41,6 +47,34 @@ implementation
 
 { TBigIntPolynomialTestCase }
 
+procedure TBigIntPolynomialTestCase.TestCreateWithDegree(const ACoefficients: array of TBigInt; const ADegree: Integer);
+var
+  a: TBigIntPolynomial;
+begin
+  a := TBigIntPolynomial.Create(ACoefficients);
+  AssertEquals('Degree of created polynomial incorrect.', ADegree, a.Degree);
+end;
+
+procedure TBigIntPolynomialTestCase.TestCreate;
+begin
+  TestCreateWithDegree([992123, 7, 20, 4550022], 3);
+end;
+
+procedure TBigIntPolynomialTestCase.TestCreateDegreeOne;
+begin
+  TestCreateWithDegree([4007], 0);
+end;
+
+procedure TBigIntPolynomialTestCase.TestCreateDegreeZero;
+begin
+  TestCreateWithDegree([], -1);
+end;
+
+procedure TBigIntPolynomialTestCase.TestCreateDegreeZeroTrim;
+begin
+  TestCreateWithDegree([0], -1);
+end;
+
 procedure TBigIntPolynomialTestCase.TestEqual;
 var
   a, b: TBigIntPolynomial;