It sounds like you want this function from Eric Lippert's blog post written in response to Generating all Possible Combinations:
public static IEnumerable<IEnumerable<T>> CartesianProduct<T>(
this IEnumerable<IEnumerable<T>> sequences)
{
IEnumerable<IEnumerable<T>> emptyProduct = new[] { Enumerable.Empty<T>() };
return sequences.Aggregate(
emptyProduct,
(accumulator, sequence) =>
from accseq in accumulator
from item in sequence
select accseq.Concat(new[] {item}));
}
That would let you write code like this:
int[][] items = {
new[] { 11001, 54010, 60621 },
new[] { 11001, 60621 },
new[] { 60621 }
};
var routes = CartesianProduct(items);
foreach (var route in routes)
Console.WriteLine(string.Join(", ", route));
And get output like this:
11001, 11001, 60621
11001, 60621, 60621
54010, 11001, 60621
54010, 60621, 60621
60621, 11001, 60621
60621, 60621, 60621
EDIT: Here's the VB.NET version (in VS2010)
Imports System.Runtime.CompilerServices
Module Module1
<Extension()>
Private Function CartesianProduct(Of T)(
ByVal sequences As IEnumerable(Of IEnumerable(Of T))) _
As IEnumerable(Of IEnumerable(Of T))
Dim emptyProduct As IEnumerable(Of IEnumerable(Of T)) =
New IEnumerable(Of T)() {Enumerable.Empty(Of T)()}
Return sequences.Aggregate(
emptyProduct,
Function(accumulator, sequence)
Return (From accseq In accumulator
From item In sequence
Select accseq.Concat(New T() {item}))
End Function)
End Function
Sub Main(ByVal args As String())
Dim items = New Integer()() {New Integer() {11001, 54010, 60621},
New Integer() {11001, 60621},
New Integer() {60621}}
Dim routes = items.CartesianProduct()
Dim route As IEnumerable(Of Integer)
For Each route In routes
Console.WriteLine(String.Join(", ", route))
Next
End Sub
End Module
Of course, if you don't want any LINQ whatsoever, here's a completely LINQ-free recursive implementation:
public static IEnumerable<IEnumerable<T>> CartesianProduct<T>(
this IEnumerable<IEnumerable<T>> sequences)
{
var accum = new List<T[]>();
var list = sequences.ToList();
if (list.Count > 0)
CartesianRecurse(accum, new Stack<T>(), list, list.Count - 1);
return accum;
}
static void CartesianRecurse<T>(List<T[]> accum, Stack<T> stack,
List<IEnumerable<T>> list, int index)
{
foreach (T item in list[index])
{
stack.Push(item);
if (index == 0)
accum.Add(stack.ToArray());
else
CartesianRecurse(accum, stack, list, index - 1);
stack.Pop();
}
}
It doesn't return the items in the same order as the first function, but is otherwise functionally identical. If you don't like LINQ or recursion, here's a single LINQ-less method that does the same thing as the recursive version:
public static IEnumerable<IEnumerable<T>> CartesianProduct<T>(
this IEnumerable<IEnumerable<T>> sequences)
{
var accum = new List<T[]>();
var list = sequences.ToList();
if (list.Count > 0)
{
var enumStack = new Stack<IEnumerator<T>>();
var itemStack = new Stack<T>();
int index = list.Count - 1;
var enumerator = list[index].GetEnumerator();
while (true)
if (enumerator.MoveNext())
{
itemStack.Push(enumerator.Current);
if (index == 0)
{
accum.Add(itemStack.ToArray());
itemStack.Pop();
}
else
{
enumStack.Push(enumerator);
enumerator = list[--index].GetEnumerator();
}
}
else
{
if (++index == list.Count)
break;
itemStack.Pop();
enumerator = enumStack.Pop();
}
}
return accum;
}