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List of combinations

Posted on 2014-11-24
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Last Modified: 2016-02-18
After help with code

Need to list all combinations in groups of 3 where number cannot list more than once in the 3 number combo

Eg GOOD

1 - 2 - 3
1 - 2 - 4
1 - 2 - 5

Bad

1-1-1
1-1-2
1-1-3
1-2-1
etc
0
Comment
Question by:Jason
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14 Comments
 
LVL 26

Expert Comment

by:Shaun Kline
ID: 40462001
That would normally be done using three loops:
For loop1 as integer = 1 to 10
   For loop2 as integer = loop1 + 1 to 10
      For loop3 as integer = loop 2 + 1 to 10
<your action here>
      Next
  Next
Next

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0
 

Author Comment

by:Jason
ID: 40462019
Don't think that will work
Eg
2-1-3
Doesn't fit the formula
0
 

Author Comment

by:Jason
ID: 40462027
Eg combos for 1 to 3
123
132
213
231
321
312
0
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LVL 26

Expert Comment

by:Shaun Kline
ID: 40462046
Ok...Something like this?
For loop1 as integer = 1 to 10
   For loop2 as integer = 1 to 10
      If loop1 = loop2 Then Continue For
      For loop3 as integer = 1 to 10
          If loop1 = loop3 OrElse loop2 = loop3 Then Continue For
<your action here>
      Next
  Next
Next

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0
 
LVL 13

Expert Comment

by:Philip Pinnell
ID: 40462080
Dim comb As String = ""

For a1 As Integer = 1 To 9
      For a2 As Integer = 1 To 9
            For a3 As Integer = 1 To 9
                  If a1 <> a2 AndAlso a1 <> a3 AndAlso a2 <> a3 Then
                        comb = a1.ToString() & "-" & a2.ToString() & "-" & a3.ToString()
' save each value as you wish here
                  End If

            Next
      Next
Next
0
 
LVL 34

Assisted Solution

by:it_saige
it_saige earned 2000 total points
ID: 40462204
Or you could use linq:
Module Module1
	Sub Main()
		Dim combinations = (From a As Integer In Enumerable.Range(1, 9) Let a1 As Integer = a _
		    From b As Integer In Enumerable.Range(1, 9) Let b1 As Integer = b _
		    From c As Integer In Enumerable.Range(1, 9) Let c1 As Integer = c _
		    Where Not a1.Equals(b1) AndAlso Not a1.Equals(c1) _
		    AndAlso Not b1.Equals(a1) AndAlso Not b1.Equals(c1) _
		    AndAlso Not c1.Equals(a1) AndAlso Not c1.Equals(b1) _
		    Select New Integer() {a1, b1, c1})
		For Each combination In combinations
			Console.WriteLine(String.Format("{0} - {1} - {2}", combination(0), combination(1), combination(2)))
		Next
		Console.ReadLine()
	End Sub
End Module

Open in new window


Produces the following sample output:Capture.JPG
-saige-
0
 
LVL 34

Expert Comment

by:it_saige
ID: 40462207
Modifying for the test case 1 to 3:
Module Module1
	Sub Main()
		Dim combinations = (From a As Integer In Enumerable.Range(1, 3) Let a1 As Integer = a _
		    From b As Integer In Enumerable.Range(1, 3) Let b1 As Integer = b _
		    From c As Integer In Enumerable.Range(1, 3) Let c1 As Integer = c _
		    Where Not a1.Equals(b1) AndAlso Not a1.Equals(c1) _
		    AndAlso Not b1.Equals(a1) AndAlso Not b1.Equals(c1) _
		    AndAlso Not c1.Equals(a1) AndAlso Not c1.Equals(b1) _
		    Select New Integer() {a1, b1, c1})
		For Each combination In combinations
			Console.WriteLine(String.Format("{0} - {1} - {2}", combination(0), combination(1), combination(2)))
		Next
		Console.ReadLine()
	End Sub
End Module

Open in new window


Produces the following output:Capture.JPG
-saige-
0
 
LVL 34

Expert Comment

by:it_saige
ID: 40462232
And for the coupe de gras, if you feel so inclined, you can create a method and add parameters so that you can provide your bookend integers, e.g. -
Module Module1
	Private Function GetCombinations(ByVal start As Integer, ByVal [end] As Integer) As IEnumerable(Of Integer())
		Dim combinations = (From a As Integer In Enumerable.Range(start, [end]) Let a1 As Integer = a _
		  From b As Integer In Enumerable.Range(start, [end]) Let b1 As Integer = b _
		  From c As Integer In Enumerable.Range(start, [end]) Let c1 As Integer = c _
		  Where Not a1.Equals(b1) AndAlso Not a1.Equals(c1) _
		  AndAlso Not b1.Equals(a1) AndAlso Not b1.Equals(c1) _
		  AndAlso Not c1.Equals(a1) AndAlso Not c1.Equals(b1) _
		  Select New Integer() {a1, b1, c1})
		Return combinations
	End Function

	Sub Main()
		For Each combination In GetCombinations(1, 3)
			Console.WriteLine(String.Format("{0} - {1} - {2}", combination(0), combination(1), combination(2)))
		Next
		Console.ReadLine()
	End Sub
End Module

Open in new window


-saige-
0
 
LVL 63

Expert Comment

by:Fernando Soto
ID: 40462349
Hi Renegade_AD;

Try this function out to see if it gives you what you are looking for.

public List<string> GeneratePermutations(string value)
{
    if (value.Length > 1)
    {
        return (from character in value
                from permutation in GeneratePermutations(value.Remove(value.IndexOf(character), 1))
                select string.Format("{0} - {1}", character, permutation)).ToList();
    }
    else
    {
        return new List<string>() { value };
    }
}

Open in new window


To call it you can do this,

List<string> results = GeneratePermutations("123");

or

List<string> results = GeneratePermutations(123.ToString());
0
 
LVL 34

Expert Comment

by:it_saige
ID: 40462419
Here is Fernando's method in VB.NET:
Module Module1
	Private Function GetCombinations(ByVal start As Integer, ByVal [end] As Integer) As IEnumerable(Of Integer())
		Dim combinations = (From a As Integer In Enumerable.Range(start, [end]) Let a1 As Integer = a _
		  From b As Integer In Enumerable.Range(start, [end]) Let b1 As Integer = b _
		  From c As Integer In Enumerable.Range(start, [end]) Let c1 As Integer = c _
		  Where Not a1.Equals(b1) AndAlso Not a1.Equals(c1) _
		  AndAlso Not b1.Equals(a1) AndAlso Not b1.Equals(c1) _
		  AndAlso Not c1.Equals(a1) AndAlso Not c1.Equals(b1) _
		  Select New Integer() {a1, b1, c1})
		Return combinations
	End Function

	Private Function GeneratePermutations(ByVal value As String) As List(Of String)
		If value.Length > 1 Then
			Return (From character In value _
			    From permutation In GeneratePermutations(value.Remove(value.IndexOf(character), 1)) _
			    Select String.Format("{0} - {1}", character, permutation)).ToList()
		Else
			Return New List(Of String) From {value}
		End If
	End Function

	Sub Main()
		Console.WriteLine("Using get combinations...")
		For Each combination In GetCombinations(1, 3)
			Console.WriteLine(String.Format("{0} - {1} - {2}", combination(0), combination(1), combination(2)))
		Next

		Console.WriteLine()
		Console.WriteLine("Using generate permutations...")
		For Each permutation In GeneratePermutations("123")
			Console.WriteLine(permutation)
		Next
		Console.ReadLine()
	End Sub
End Module

Open in new window


Produces the following output:Capture.JPG
BTW, nice use of recursion Fernando... ;)

-saige-
0
 
LVL 63

Expert Comment

by:Fernando Soto
ID: 40462475
Hi Renegade_AD;

As -saige- pointed out that my solution was in C# I resubmit it in my version of VB .Net.

Public Function GeneratePermutations(ByVal value As String) As List(Of String)
    if value.Length > 1
        Return (From character in value
                from permutation in GeneratePermutations(value.Remove(value.IndexOf(character), 1))
                Select String.Format("{0} - {1}", character, permutation)).ToList()
    else
        Return New List(Of String)() From { value }
    End If
End Function

Open in new window


To call it you can do this,

Dim results As List(Of String) = GeneratePermutations("123");

or

Dim results As List(Of String) = GeneratePermutations(123.ToString());

@ -saige-, Thank you.
0
 

Author Comment

by:Jason
ID: 40463156
@it saige
your code works great.  one adjustment what about if i had a rage of numbers and i want them in combinations of 3
ie user enters
5
9  
7
1
3
8

output is all combination of these numbers in groups of 3
how you the code look for this
0
 
LVL 34

Accepted Solution

by:
it_saige earned 2000 total points
ID: 40463202
Thats simple enough.  Now you are dealing with a distinct *list* of integers and a *list* is enumerable, so in this case we would not use the Enumerable.Range but rather the list of distinct numbers itself, e.g. -
Module Module1
	Private Function GetCombinations(ByVal numbers As IEnumerable(Of Integer)) As IEnumerable(Of Integer())
		Dim combinations = (From a As Integer In numbers _
		    From b As Integer In numbers _
		    From c As Integer In numbers _
		    Where Not a.Equals(b) AndAlso Not a.Equals(c) _
		    AndAlso Not b.Equals(a) AndAlso Not b.Equals(c) _
		    AndAlso Not c.Equals(a) AndAlso Not c.Equals(b) _
		    Select New Integer() {a, b, c})
		Return combinations
	End Function

	Sub Main()
		Dim numbers As Integer() = {5, 9, 7, 1, 3, 8}
		Console.WriteLine("Using distinct combinations...")
		For Each combination In GetCombinations(numbers)
			Console.WriteLine(String.Format("{0} - {1} - {2}", combination(0), combination(1), combination(2)))
		Next
		Console.ReadLine()
	End Sub
End Module

Open in new window


Produces the following output:Capture.JPG
Now we can simplify the original method by just calling the new GetCombinations method with the ranged enumerable:
Module Module1
	Private Function GetCombinations(ByVal start As Integer, ByVal [end] As Integer) As IEnumerable(Of Integer())
		Return GetCombinations(Enumerable.Range(start, [end]))
	End Function

	Private Function GetCombinations(ByVal numbers As IEnumerable(Of Integer)) As IEnumerable(Of Integer())
		Dim combinations = (From a As Integer In numbers _
		    From b As Integer In numbers _
		    From c As Integer In numbers _
		    Where Not a.Equals(b) AndAlso Not a.Equals(c) _
		    AndAlso Not b.Equals(a) AndAlso Not b.Equals(c) _
		    AndAlso Not c.Equals(a) AndAlso Not c.Equals(b) _
		    Select New Integer() {a, b, c})
		Return combinations
	End Function

	Sub Main()
		Dim numbers As Integer() = {5, 9, 7, 1, 3, 8}
		Console.WriteLine("Using get combinations...")
		For Each combination In GetCombinations(1, 3)
			Console.WriteLine(String.Format("{0} - {1} - {2}", combination(0), combination(1), combination(2)))
		Next
		Console.WriteLine("Press any key to continue...")
		Console.ReadLine()

		Console.WriteLine()
		Console.WriteLine("Using distinct combinations...")
		For Each combination In GetCombinations(numbers)
			Console.WriteLine(String.Format("{0} - {1} - {2}", combination(0), combination(1), combination(2)))
		Next
		Console.ReadLine()
	End Sub
End Module

Open in new window


-saige-
0
 

Author Closing Comment

by:Jason
ID: 40463961
Great help
0

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