WikiFunctions.Diff.LCSidx C# (CSharp) Method

        private void LCSidx(IList a, IList b, out IntList am, out IntList bm)
        {
            IntList match = _longestCommonSubsequence(a, b);
            am = new IntList();
            for (int i = 0; i < match.Count; i++)
                if (match[i] != -1)
                    am.Add(i);
            bm = new IntList();
            for (int vi = 0; vi < am.Count; vi++)
                bm.Add(match[am[vi]]);
        }