Question

i have two numbers 1,2 in one array.Now i want to generate all the possible combinations of arrays(of size=5) like

1,2,0,0,0 ||
2,1,0,0,0 ||
1,0,2,0,0
.
.
.
.
.

I tried to write a recursive function but its not working

Now I want to solve this using LINQ because the code will be considerably small.

Please help me

Answer 1

LINQ is excellent for searching; it’s much worse at generating, so it is a wrong tool for the job. So is recursion (although it is a better choice than LINQ). What you need is two nested loops, like this:

var elements = new [] {1, 2};
for (var i = 0 ; i != 5 ; i++) {
    for (int j = 0 ; j != 5 ; j++) {
        if (i == j) continue;
        var data = new int[5];
        data[i] = elements[0];
        data[j] = elements[1];
        ProcessCombination(data);
    }
}

Here is what the code does: at each iteration of the inner loop it places the first and the second element from the elements array at distinct positions i and j. Nested loops go from 0 to 5, making sure all position combinations are covered.