[Twitter] All possible pickings

Question:

Given n Sets of choices: (1, 2, 3), (A, B, c), (I, II, III).

You pick one element from each set of choices. Generate all possible pickings.

http://www.glassdoor.com/Interview/ Given-n-sets-of-choices-1-2-3-2-3-4-4-5-you-pick-one-element-from-each-set-of-choices-generate-all-possibl-qtn_ 218899.htm

Private list<list<string>> generateallpickings (String[][] pool) {     List<List<String>> result = new ArrayList<> ();     help (Pool, 0, new arraylist<string> (),  result);     return  result;} Private void help (string[][] pool,                    int group,                   List<String> cur,                   List< List<string>> result) {    if  (Cur.size ()  == pool.length)     {        result.add (new ArrayList< string> (cur));     }    if  (group >= pool.length)      {        return;    }         // now we are looking at pool[group], put  each elements into the cur    for  (int i = 0  ; i < pool[group].length ; i ++)     {         cur.add (Pool[group][i]);         Help (Pool, group + 1, cur, result);         Cur.remove (Cur.size ()  - 1);     }}

[Twitter] All possible pickings