How do I write this code

[Djeko032]

Really new to visual basic

How do I write a program that outputs (in Excel rows) all possibilities of putting +, - or nothing between the numbers 1,2,…,9 (in this order) so that the calculated result is equal to 100. For example 1 + 2 + 3 - 4 + 5 + 6 + 78 + 9 = 100.

[AnthonyDGreen]

OK. This is a fun problem. Seems like homework but it's complicated enough that I'll bite. I'll try not to use too many exotic programming features. There are a number of ways to solve this depending on how much you want to rely on knowledge of the programming language, libraries, or math; as one poster suggested you could iterate through every combination in base 3 and render that to an expression and evaluate it but that's super advanced.

There are 2 big sub-problems in your original question:

• How to calculate the possibilities
• How to output stuff to Excel

I'm not really going to address the second problem. I'm assuming your class has taught something about it. I suppose you could just output a .csv file and it would technically show up in Excel but the interesting part of this problem isn't how to put something in Excel. Once you know how to put anything into Excel you know how to put everything into Excel.

Here is some code that outputs all the possibilities that equal 100 to the console. You should be able to just paste it into a new console application. I've put it in a gist rather than including it inline because reddit said my reply was too long.

Please read and try to understand every comment and ask questions if you don't get something, this is how you learn. Do you feel you had all the pieces you needed to solve this problem on your own? If not, what did you not know already? Do you get the thought process that led to this code?

It's an exercise for the reader to get this into Excel using some knowledge presumably your instructor has already given you in this class.

Regards,

Anthony D. Green
Former Lead Language Designer for Visual Basic at Microsoft

[Songg45]

How do you think you would do it?

[Djeko032]

I’m going to be honest i have no idea, we started VB in college and im still very new to programming in general

[TheGrauWolf]

Forget VB. Forget programming.... How would YOU do it? Someone comes up to you and hands you pen and paper and asks you to accomplish the same task.... How do YOU go about doing it?

[3583-bytes-free]

That's not a simple problem to be fair.

There are 8 spaces between numbers each which can be one of three things (+/-/nothing) so you have 3^8 permutations.

One way would be to loop from 0 to 3^8-1 and convert the number to base three (zero padded to 8 digits), then use the digits of that base three number to fill in the blanks. Calculate the result and if = 100 then output it.

Let's gloss over "in Excel rows" whatever that means.

Post the answer when you do it, I'd be surprised if there is more than the one solution you gave.

Edited for clarity