algorithm - Permutations in VBA Excel

Question

I am trying to generate all the possible combinations of an array of characters. The input array has n characters, 5 <= n <= 7, and I would like to generate a second array A( C( n , 5 ) , 5 ) that contains all the C( n , 5 ) combinations. The order of the characters in the array isn't important.

Here is an example: input array: { A, B, C, D, E, F } , so n = 6 output array should be:

{A B C D E},
{A B C D F},
{A B C F E},
{A B F D E},
{A F C D E},
{F B C D E},

This is pretty simple for n=5 and n=6, but gets very complicated for n=7. Does anyone know how should I make this ?

Thanks

Answer 1

Solve it recursively.

For example, your n = 7 case. In the outer layer, you start with {A, B, C, D, E, F, G}. From this, you take one letter out; a different one 7 times. So you have 7 elements in this output array set, each with 6 letters: {A, B, C, D, E, F}, {A, B, C, D, E, G} etc.

For each of these outputs, you then further reduce using the same algorithm. You already know how to deal with {A, B, C, D, E, F}.