Microsoft Small Basic

Program Listing: SZP003-0

List Program

' Maths Challenge - December 2018
' Copyright © 2018 Nonki Takahashi. The MIT License.
' Program ID SZP003-0

' Write a program that outputs all possibilities to put + or - or nothing
' between the numbers 1,2,…,9 (in this order) such that the result is 100.
' For example 1 + 2 + 3 - 4 + 5 + 6 + 78 + 9 = 100

delim="0= + ;1= - ;2=;"
For j = 0 To Math.Power(3, 8) - 1
_j = j
e = 9
For i = 8 To 1 Step -1
r = Math.Remainder(_j, 3)
e = Text.Append(i, Text.Append(delim[r], e))
_j = (_j - r) / 3
EndFor
Eval()
If ans = 100 Then
TextWindow.WriteLine(e + " = " + ans)
EndIf
EndFor

Sub Eval
' param e - expression
' return ans - answer
sign = 1
ans = 0
num = ""
For p = 1 To Text.GetLength(e)
c = Text.GetSubText(e, p, 1)
If c = "+" Then
ans = ans + sign * num
sign = 1
num = ""
ElseIf c = "-" Then
ans = ans + sign * num
sign = -1
num = ""
ElseIf c = " " Then
Else
num = Text.Append(num, c)
EndIf
EndFor
ans = ans + sign * num
EndSub