🎉 Exercism Research is now launched. Help Exercism, help science and have some fun at research.exercism.io 🎉
Avatar of Neftali

Neftali's solution

to Secret Handshake in the Delphi Pascal Track

Published at Jan 23 2020 · 0 comments
Instructions
Test suite
Solution

There are 10 types of people in the world: Those who understand binary, and those who don't.

You and your fellow cohort of those in the "know" when it comes to binary decide to come up with a secret "handshake".

1 = wink
10 = double blink
100 = close your eyes
1000 = jump


10000 = Reverse the order of the operations in the secret handshake.

Given a decimal number, convert it to the appropriate sequence of events for a secret handshake.

Here's a couple of examples:

Given the input 3, the function would return the array ["wink", "double blink"] because 3 is 11 in binary.

Given the input 19, the function would return the array ["double blink", "wink"] because 19 is 10011 in binary. Notice that the addition of 16 (10000 in binary) has caused the array to be reversed.

Testing

In order to run the tests for this track, you will need to install DUnitX. Please see the installation instructions for more information.

Loading Exercises into Delphi

If Delphi is properly installed, and *.dpr file types have been associated with Delphi, then double clicking the supplied *.dpr file will start Delphi and load the exercise/project. control + F9 is the keyboard shortcut to compile the project or pressing F9 will compile and run the project.

Alternatively you may opt to start Delphi and load your project via. the File drop down menu.

When Questions Come Up

We monitor the Pascal-Delphi support room on gitter.im to help you with any questions that might arise.

Submitting Exercises

Note that, when trying to submit an exercise, make sure the exercise file you're submitting is in the exercism/delphi/<exerciseName> directory.

For example, if you're submitting ubob.pas for the Bob exercise, the submit command would be something like exercism submit <path_to_exercism_dir>/delphi/bob/ubob.pas.

Source

Bert, in Mary Poppins http://www.imdb.com/title/tt0058331/quotes/qt0437047

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you may request help from a mentor.

uSecretHandshakeTests.pas

unit uSecretHandshakeTests;

interface
uses
  DUnitX.TestFramework;

const
  CanonicalVersion = '1.2.0.1';

type
  [TestFixture]
  SecretHandshakeTest = class(TObject)
  private
    procedure CompareArrays(aExpected, aActual: TArray<string>);
  public
    [Test]
//    [Ignore('Comment the "[Ignore]" statement to run the test')]
    procedure wink_for_1;

    [Test]
    [Ignore]
    procedure double_blink_for_10;

    [Test]
    [Ignore]
    procedure close_your_eyes_for_100;

    [Test]
    [Ignore]
    procedure jump_for_1000;

    [Test]
    [Ignore]
    procedure combine_two_actions;

    [Test]
    [Ignore]
    procedure reverse_two_actions;

    [Test]
    [Ignore]
    procedure reversing_one_action_gives_the_same_action;

    [Test]
    [Ignore]
    procedure reversing_no_actions_still_gives_no_actions;

    [Test]
    [Ignore]
    procedure all_possible_actions;

    [Test]
    [Ignore]
    procedure reverse_all_possible_actions;

    [Test]
    [Ignore]
    procedure do_nothing_for_zero;
  end;

implementation
uses uSecretHandshake;


{ SecretHandshakeTest }

procedure SecretHandshakeTest.all_possible_actions;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 4);
  Expected[0] := 'wink';
  Expected[1] := 'double blink';
  Expected[2] := 'close your eyes';
  Expected[3] := 'jump';

  Actual := TSecretHandshake.commands(15);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.close_your_eyes_for_100;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 1);
  Expected[0] := 'close your eyes';

  Actual := TSecretHandshake.commands(4);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.combine_two_actions;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 2);
  Expected[0] := 'wink';
  Expected[1] := 'double blink';

  Actual := TSecretHandshake.commands(3);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.double_blink_for_10;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 1);
  Expected[0] := 'double blink';

  Actual := TSecretHandshake.commands(2);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.do_nothing_for_zero;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 0);

  Actual := TSecretHandshake.commands(0);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.jump_for_1000;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 1);
  Expected[0] := 'jump';

  Actual := TSecretHandshake.commands(8);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.reverse_all_possible_actions;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 4);
  Expected[0] := 'jump';
  Expected[1] := 'close your eyes';
  Expected[2] := 'double blink';
  Expected[3] := 'wink';

  Actual := TSecretHandshake.commands(31);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.reverse_two_actions;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 2);
  Expected[0] := 'double blink';
  Expected[1] := 'wink';

  Actual := TSecretHandshake.commands(19);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.reversing_no_actions_still_gives_no_actions;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 0);

  Actual := TSecretHandshake.commands(16);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.reversing_one_action_gives_the_same_action;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 1);
  Expected[0] := 'jump';

  Actual := TSecretHandshake.commands(24);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.wink_for_1;
var Expected,
    Actual: TArray<string>;
begin
  SetLength(Expected, 1);
  Expected[0] := 'wink';

  Actual := TSecretHandshake.commands(1);

  CompareArrays(Expected, Actual);
end;

procedure SecretHandshakeTest.CompareArrays(aExpected, aActual: TArray<string>);
var i: integer;
begin
  Assert.AreEqual(length(aExpected), length(aActual));
  for i := Low(aExpected) to High(aExpected) do
    Assert.AreEqual(aExpected[i], aActual[i]);
end;

initialization
  TDUnitX.RegisterTestFixture(SecretHandshakeTest);
end.
unit uSecretHandshake;

interface

uses
  System.Generics.Collections;

type
  TSecretHandshake = class
  private
    class function InitializeHandShakeValues:TDictionary<Integer, string>;
    class function IntToBin(ANumber:integer): string;
  public
    class function commands(const ANumber:integer):TArray<string>;
  end;


implementation

uses
  System.Sysutils, Data.FmtBcd;

{ TSecretHandshake }

class function TSecretHandshake.IntToBin(ANumber:integer): string;
begin
  Result := '';
  while (ANumber > 0) do begin
    Result := Integer(Odd(ANumber)).ToString + Result;
    ANumber := ANumber DIV 2;
  end;
end;

class function TSecretHandshake.InitializeHandShakeValues:TDictionary<Integer, string>;
begin
  Result := TDictionary<Integer, string>.Create(5);
  Result.Add(1, 'wink');
  Result.Add(2, 'double blink');
  Result.Add(3, 'close your eyes');
  Result.Add(4, 'jump');
  Result.Add(5, 'reverse');
end;


class function TSecretHandshake.commands(const ANumber: integer): TArray<string>;
var
  i:integer;
  sbin:string;
  l:TList<string>;
  HandshakeValues:TDictionary<Integer, string>;
begin
  l := TList<string>.Create;      // List for result
  HandshakeValues := TSecretHandshake.InitializeHandShakeValues;  // Dictionary

  try
    sbin := TSecretHandshake.IntToBin(ANumber);  // convert to binary
    for i := High(sbin) downto Low(sbin) do
      if sbin[i] = '1' then
        // Must reverse ?
        if (i = 1) and (Length(sbin) = (HandshakeValues.Count)) then
          l.Reverse
        else
          l.Add(HandshakeValues.Items[Length(sbin) - i + 1]);
    // convert result
    Result := l.ToArray;
  finally
    FreeAndNil(HandshakeValues);
    FreeAndNil(l);
  end;
end;


end.

Community comments

Find this solution interesting? Ask the author a question to learn more.

What can you learn from this solution?

A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

  • What compromises have been made?
  • Are there new concepts here that you could read more about to improve your understanding?