Possible combination of specific size

[imdadullah]

I have list of numbers like
3100002
11200002
11200011
12010011
12010020
20110002
20110101
21001020
21001110
30000300
100300020
.
.
.
.

I need all possible combinations of specific size depending on some conditions.
size of combination can vary from 3 to 25.

I am doing it with nested for loop but its time consuming as number of inner loop increases.

I need some code help related to this problem.
Code help can be for
Matlab
Mathematica
C
Java

Plz guide...

 

[imdadullah]

is there any expert to answer this.....