Finding Distinct Values In Array?

I have a database which need to be assigned into array arr()(), e.g.

arr(0)(0) = aa arr(1)(0) = ab arr(2)(0) = aa
arr(0)(1) = bb arr(1)(1) = ba arr(2)(1) = ba
arr(0)(2) = cc arr(1)(2) = cc arr(2)(2) = cc

I need to find distinct / unique value in each arr(k)(0), arr(k)(1), arr(k)(2); where k=0..2. Then i need to insert the result into array cat as follows:

cat(0)(0) = {aa} cat(0)(1) = {ab}
cat(1)(0) = {bb} cat(1)(1) = {ba}
cat(2)(0) = {cc}

I've tried code below but it doesn't work. The assigning process into array arr()() from DB is OK. Problem only come up if I try to find the distinct value (If Not (cat(j).Contains(ds.Tables(0).Rows(i).Item(j))) ... End If).

For i = 0 To 2
list(i) = New Integer(3) {}
For j = 0 To 2

[Code].....