need help with recursive statements

Question

0.00/5 (No votes)

See more:

hi, I kinda suck at coding recursive functions !
the problem I need to solve is this :
in a dart game a person can score :7,15,19,23,29 or 37 points in each shot
find the combinations in which a player scores 100 points with exactly six shots.
so I wrote this : (vb.net )

VB

arr(0) = 7
     arr(1) = 15
     arr(2) = 19
     arr(3) = 23
     arr(4) = 29
     arr(5) = 37

     For i = 0 To 5

         For j = 0 To 5
             For k = 0 To 5

                 For l = 0 To 5

                     For m = 0 To 5


                         For n = 0 To 5

                             sum = arr(i) + arr(j) + arr(k) + arr(l) + arr(m) + arr(n)
                             If sum = 100 Then
                                 My.Computer.FileSystem.WriteAllText("C:\dar.txt", arr(i) & "   " & arr(j) & "   " & arr(k) & "   " & arr(l) & "   " & arr(m) & "   " & arr(n) & vbNewLine, True)
                             End If
                         Next
                     Next

                 Next


             Next


         Next

     Next

but it is a very poor solution as you can see !
how can I do this using recursion ?
I first tried to use recursion but it computer only the first combination (7 7 7 7 7 7 ) and then it would do (15 7 7 7 7 7 ) forever

thank you very much !!

Posted 25-Apr-14 1:41am

EbolaHost

Updated 25-Apr-14 3:04am

v2

Add a Solution

Comments

Sergey Alexandrovich Kryukov 25-Apr-14 7:52am

This is not C++, why this tag? Please remove it.<br>
Looking at the code does not make sense before you explain what you are going to achieve. "So I wrote this" does not seem to be related to your explanation.<br>
This is not called "recursion".
—SA

EbolaHost 25-Apr-14 9:06am

you're right about the c++
what I want to achieve is to 'find the combinations in which a player scores 100 points with exactly six shots.' and it's preety obvious from the code even for a rookie like me .
I know this code isn't recursive but uses iteration instead !
but I want the recursive version of the code...that's all :)

2 solutions

Solution 1

That isn't recursion, that's iteration.
To do this recursively, you need a method which accepts a list of possible shots and a target value.
The method then takes one of the shots from the list, and passes the remainder and the new target to itself, by calling itself - it uses itself to work out the rest of the combinations.

I'm not going to go into full details - that would be a lot of work for me (and frankly I can't be bothered to do that at the moment, plus it wouldn;t help you to be given teh solution) but look at a simpler example, and it might make sense:

VB

Private Function factorial(value As Integer) As Integer
    If value <= 1 Then
        Return 1
    End If
    Return value * factorial(value - 1)
End Function

5! is 5 * 4!, which is 5 * (4 * 3!) which is 5 * (4 * (3 * 2!)) and so forth, so it calls itself to work out the other "iterations".

When you understand how that works, then start looking at your problem - it's more complicated, but not a lot when you get your head round it.

Posted 25-Apr-14 2:11am

OriginalGriff

Add a Solution

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Matt T Heffron · Accepted Answer · 2014-04-25T07:57:00

OriginalGriff gives a good description of recursion, but this problem is actually much more similar to the 8-queens problem and can be solved recursively using Backtracking[^]
Here is a link to a description of the recursive backtracking for Solving 8 queen problem[^]
Once you understand this, your problem should be pretty easy to code.

need help with recursive statements

2 solutions

Solution 1

Solution 2

Add your solution here

Preview 0

need help with recursive statements

2 solutions

Solution 1

Solution 2

Add your solution here

Preview 0

Existing Members

...or Join us