Task: Zumkeller numbers




Go: package main

import "fmt"

func getDivisors(n int) []int {
    divs := []int{1, n}
    for i := 2; i*i <= n; i++ {
        if n%i == 0 {
            j := n / i
            divs = append(divs, i)
            if i != j {
                divs = append(divs, j)
            }
        }
    }
    return divs
}

func sum(divs []int) int {
    sum := 0
    for _, div := range divs {
        sum += div
    }
    return sum
}

func isPartSum(divs []int, sum int) bool {
    if sum == 0 {
        return true
    }
    le := len(divs)
    if le == 0 {
        return false
    }
    last := divs[le-1]
    divs = divs[0 : le-1]
    if last > sum {
        return isPartSum(divs, sum)
    }
    return isPartSum(divs, sum) || isPartSum(divs, sum-last)
}

func isZumkeller(n int) bool {
    divs := getDivisors(n)
    sum := sum(divs)
    
    if sum%2 == 1 {
        return false
    }
    
    if n%2 == 1 {
        abundance := sum - 2*n
        return abundance > 0 && abundance%2 == 0
    }
    
    return isPartSum(divs, sum/2)
}

func main() {
    fmt.Println("The first 220 Zumkeller numbers are:")
    for i, count := 2, 0; count < 220; i++ {
        if isZumkeller(i) {
            fmt.Printf("%3d ", i)
            count++
            if count%20 == 0 {
                fmt.Println()
            }
        }
    }
    fmt.Println("\nThe first 40 odd Zumkeller numbers are:")
    for i, count := 3, 0; count < 40; i += 2 {
        if isZumkeller(i) {
            fmt.Printf("%5d ", i)
            count++
            if count%10 == 0 {
                fmt.Println()
            }
        }
    }
    fmt.Println("\nThe first 40 odd Zumkeller numbers which don't end in 5 are:")
    for i, count := 3, 0; count < 40; i += 2 {
        if (i % 10 != 5) && isZumkeller(i) {
            fmt.Printf("%7d ", i)
            count++
            if count%8 == 0 {
                fmt.Println()
            }
        }
    }
    fmt.Println()
}





VB: Module Module1
    Function GetDivisors(n As Integer) As List(Of Integer)
        Dim divs As New List(Of Integer) From {
            1, n
        }
        Dim i = 2
        While i * i <= n
            If n Mod i = 0 Then
                Dim j = n \ i
                divs.Add(i)
                If i <> j Then
                    divs.Add(j)
                End If
            End If
            i += 1
        End While
        Return divs
    End Function

    Function IsPartSum(divs As List(Of Integer), sum As Integer) As Boolean
        If sum = 0 Then
            Return True
        End If
        Dim le = divs.Count
        If le = 0 Then
            Return False
        End If
        Dim last = divs(le - 1)
        Dim newDivs As New List(Of Integer)
        For i = 1 To le - 1
            newDivs.Add(divs(i - 1))
        Next
        If last > sum Then
            Return IsPartSum(newDivs, sum)
        End If
        Return IsPartSum(newDivs, sum) OrElse IsPartSum(newDivs, sum - last)
    End Function

    Function IsZumkeller(n As Integer) As Boolean
        Dim divs = GetDivisors(n)
        Dim sum = divs.Sum()
        REM if sum is odd can
        If sum Mod 2 = 1 Then
            Return False
        End If
        REM if n is odd use 
        If n Mod 2 = 1 Then
            Dim abundance = sum - 2 * n
            Return abundance > 0 AndAlso abundance Mod 2 = 0
        End If
        REM if n and sum are both even check if there
        Return IsPartSum(divs, sum \ 2)
    End Function

    Sub Main()
        Console.WriteLine("The first 220 Zumkeller numbers are:")
        Dim i = 2
        Dim count = 0
        While count < 220
            If IsZumkeller(i) Then
                Console.Write("{0,3} ", i)
                count += 1
                If count Mod 20 = 0 Then
                    Console.WriteLine()
                End If
            End If
            i += 1
        End While
        Console.WriteLine()

        Console.WriteLine("The first 40 odd Zumkeller numbers are:")
        i = 3
        count = 0
        While count < 40
            If IsZumkeller(i) Then
                Console.Write("{0,5} ", i)
                count += 1
                If count Mod 10 = 0 Then
                    Console.WriteLine()
                End If
            End If
            i += 2
        End While
        Console.WriteLine()

        Console.WriteLine("The first 40 odd Zumkeller numbers which don
        i = 3
        count = 0
        While count < 40
            If i Mod 10 <> 5 AndAlso IsZumkeller(i) Then
                Console.Write("{0,7} ", i)
                count += 1
                If count Mod 8 = 0 Then
                    Console.WriteLine()
                End If
            End If
            i += 2
        End While
    End Sub
End Module