BinSearch

static bool BinSearch(ref long[] N, long key)
        {
            long l = -1, r = N.Length, m = 0;
            while (l < r - 1)
            {
                m = (l + r) / 2;
                if (N[m] < key)
                    l = m;
                else
                    r = m;
            }

            if (r == N.Length)
                return false;
            else if (N[r] == key)
            {
                N[r] = -1;
                return true;
            }
            else
                return false;
        }