unit uWordy; interface uses System.SysUtils, RegularExpressions, System.Generics.Collections; type EInvalidProblem = Class(Exception); TWordy = Class private type TParsedProblem = record X: integer; Operation1: string; Y: integer; Operation2: string; Z: integer; constructor create(parsedGroups: TGroupCollection); overload; constructor create(aXValue: integer); overload; end; class var Operations: TDictionary>; class var VariableAndOperatorGroupsRegex: TRegex; class procedure buildOperations; class procedure buildVariableAndOperatorGroupsRegex; class function ParseProblem(aProblem: string): TParsedProblem; public class function Answer(aQuestion: string): integer; end; implementation uses Math; { TWordy } class function TWordy.Answer(aQuestion: string): integer; var ParsedProblem: TParsedProblem; Operation: TFunc; firstPass: integer; begin if not assigned(Operations) then begin buildOperations; buildVariableAndOperatorGroupsRegex; end; if aQuestion.Trim.IsEmpty or (aQuestion.Trim.ToUpperInvariant = 'WHAT IS?') then raise EInvalidProblem.Create('syntax error'); ParsedProblem := ParseProblem(aQuestion); if ParsedProblem.Operation1.IsEmpty then begin result := ParsedProblem.X; end else begin Operation := Operations[ParsedProblem.Operation1]; firstPass := Operation(ParsedProblem.X, ParsedProblem.Y); if ParsedProblem.Operation2.IsEmpty then result := firstPass else begin Operation := Operations[ParsedProblem.Operation2]; result := Operation(firstPass, ParsedProblem.Z); end; end; end; class procedure TWordy.BuildOperations; begin Operations := TDictionary>.Create; Operations.Add('plus', function(X: integer; Y: integer): integer begin result := X + Y; end); Operations.Add('minus', function(X: integer; Y: integer): integer begin result := X - Y; end); Operations.Add('multiplied by', function(X: integer; Y: integer): integer begin result := X * Y; end); Operations.Add('divided by', function(X: integer; Y: integer): integer begin result := X div Y; end); end; class procedure TWordy.buildVariableAndOperatorGroupsRegex; begin VariableAndOperatorGroupsRegex := TRegex.Create(format('%0:s %1:s %0:s\s*%1:s*\s*%0:s*', ['(-?\d+)','(plus|minus|multiplied by|divided by)'])); end; class function TWordy.ParseProblem(aProblem: string): TParsedProblem; var Match: TMatch; function TryGetTrailingValue(out aTrailingValue: integer): boolean; var stripPunc: string; splitProb: TArray; begin stripPunc := aProblem.Replace('?',''); splitProb := stripPunc.Split([' ']); try aTrailingValue := splitProb[high(splitProb)].ToInteger; result := true; except result := false; end; end; function ContainsValidOperations: boolean; begin result := TRegex.IsMatch(aProblem, '(plus|minus|multiplied by|divided by)') end; function ContainsDoubledUpOperations: boolean; var lMatch: TMatch; begin result := false; lMatch := TRegex.Match(aProblem, '(plus|minus|multiplied by|divided by)'); result := lMatch.Groups.Count > 1; end; var lTrailingValue: integer; begin Match := VariableAndOperatorGroupsRegex.Match(aProblem); if Match.Groups.Count = 0 then begin if not ContainsDoubledUpOperations and aProblem.StartsWith('What is') and TryGetTrailingValue(lTrailingValue) then exit(TParsedProblem.create(lTrailingValue)) else if ContainsValidOperations then raise EInvalidProblem.Create('syntax error') else raise EInvalidProblem.Create('unknown operation'); end; result := TParsedProblem.create(Match.Groups); end; { TWordy.TParsedProblem } constructor TWordy.TParsedProblem.create(aXValue: integer); begin X := aXValue; end; constructor TWordy.TParsedProblem.create(parsedGroups: TGroupCollection); var i: integer; parsedItems: TList; parsedItemsArray: TArray; begin parsedItems := TList.Create; for i := 1 to parsedGroups.Count - 1 do begin if parsedGroups[i].Success then parsedItems.Add(parsedGroups[i].Value) else parsedItems.Add(''); end; parsedItemsArray := parsedItems.ToArray; Setlength(parsedItemsArray, 5); X := parsedItemsArray[0].ToInteger; Operation1 := parsedItemsArray[1]; Y := parsedItemsArray[2].ToInteger; Operation2 := parsedItemsArray[3]; if (parsedItemsArray[4] <> '') then begin if Operation2.IsEmpty then raise EInvalidProblem.Create('syntax error'); Z := parsedItemsArray[4].ToInteger end; end; end.