Module Module1

    Sub Main()

        Call russianPeasantAlgorithm()
        Call loopExamples()
        Call calculatePi()
        Call findPrimeNumbers()
        Call randomPlayerGame()

    End Sub

    Sub russianPeasantAlgorithm()
        Console.Write("Enter the first integer: ")
        Dim x As Integer = Console.ReadLine()
        Console.Write("Enter the second integer: ")
        Dim y As Integer = Console.ReadLine()
        Dim z As Integer = 0
        While x > 0
            If (x Mod 2) = 1 Then
                z = z + y
            End If
            x = x \ 2
            y = y * 2
        End While
        Console.WriteLine("Answer = " & CStr(z))

        Console.WriteLine("Press any key...")
        Console.Read()

    End Sub

    'Loop examples: While..Do, Repeat..Until, For..Next, nested For..Next
    Sub loopExamples()
        Dim counter As Integer
        Dim startTime As DateTime
        Dim endTime As DateTime

        'While... End While
        Console.WriteLine("While Loop example")

        counter = 0
        While counter < 10
            counter = counter + 1
            Console.WriteLine("counter is: " & CStr(counter))
        End While

        'Repeat... Until
        Console.WriteLine(vbCrLf & "Repeat Until example")

        counter = 0
        Do
            counter = counter + 1
            Console.WriteLine("counter is: " & CStr(counter))
        Loop Until counter = 10

        'For... End For
        Console.WriteLine(vbCrLf & "For Next example")

        For i = 1 To 10 Step 1
            Console.WriteLine("counter is: " & CStr(i))
        Next

        'Nested For... End For
        Console.WriteLine(vbCrLf & "Nested For Next example")
        For i = 1 To 10
            For j = 1 To 10
                Console.WriteLine("Counters are: i=" & CStr(i) & ", j=" & CStr(j))
            Next
        Next

        Console.WriteLine(vbCrLf & "Press any key to continue..." & vbCrLf)
        Console.ReadKey()

        'Count interations
        counter = 0
        startTime = DateTime.Now
        Do While counter < 1000000000
            counter = counter + 1
        Loop
        endTime = DateTime.Now
        Console.WriteLine(vbCrLf & CStr(counter) & " iterations performed in " & CStr(endTime.Subtract(startTime).TotalSeconds) & " seconds")

        Console.WriteLine(vbCrLf & "Press any key to continue..." & vbCrLf)
        Console.ReadKey()

    End Sub

    'Use series to calculate Pi and stop when is within 0.00000001 of actual value
    Sub calculatePi()
        Dim Pi As Double
        Dim calcPi As Double
        Dim loopCounter As Long
        Dim sign As Long
        Dim primeCount As Integer = 0

        Pi = Math.PI
        calcPi = 0

        For i = 1 To 100
            calcPi = calcPi + (2 * (i Mod 2) - 1) * (4 * 1 / ((2 * i) - 1))
            Console.WriteLine("Pi after " & i & " iterations = " & calcPi)
        Next

        ' Find Pi
        calcPi = 0
        loopCounter = 0

        While (Math.Abs(Pi - calcPi) > 0.00000001)
            loopCounter = loopCounter + 1
            sign = 2 * (loopCounter Mod 2) - 1
            calcPi = calcPi + sign * 4 / (2 * loopCounter - 1)
        End While

        Console.Write(vbCrLf & "It took " & loopCounter & " iterations to find Pi = " & calcPi)

        Console.WriteLine(vbCrLf & vbCrLf & "Press any key to continue..." & vbCrLf)
        Console.ReadKey()

    End Sub

    ' Find first 1000 prime numbers with nested WHILE..ENDWHILE loops
    Sub findPrimeNumbers()
        Dim primeCount As Integer = 0
        Dim thisNumber As Integer = 1
        Dim divideNumber As Integer

        Console.WriteLine("The first 1000 prime numbers are:")
        While primeCount <= 1000
            thisNumber += 1
            divideNumber = 2
            While divideNumber < thisNumber
                If thisNumber Mod divideNumber = 0 Then
                    Exit While
                End If
                divideNumber += 1
            End While
            If thisNumber = divideNumber Then
                primeCount += 1
                Console.Write(" " & thisNumber)
            End If
        End While

        Console.WriteLine(vbCrLf & vbCrLf & "Press any key to continue..." & vbCrLf)
        Console.ReadKey()

    End Sub

    'Players lose lives based in random number range
    'Uses Rnd() function which outputs a number between 0 and 1
    'Players start with 100 lives each
    Sub randomPlayerGame()
        Dim player1Score As Integer = 100
        Dim player2Score As Integer = 100
        Dim loopCount As Integer = 0

        Do
            loopCount = loopCount + 1

            'output random number between 1 and 6
            player1Score = player1Score - (5 * Rnd() + 1)

            'output random number between 1 and 4
            player2Score = player2Score - (3 * Rnd() + 1)

            Console.WriteLine("Score after round " & loopCount & " are Player1: " & player1Score & ", Player2: " & player2Score)

        Loop Until (player1Score <= 0 Or player2Score <= 0)

        If player1Score < player2Score Then
            Console.WriteLine("The winner is Player2")
        Else
            Console.WriteLine("The winner is Player1")
        End If

        Console.WriteLine(vbCrLf & "Press any key to continue..." & vbCrLf)
        Console.ReadKey()

    End Sub

End Module