Ints sort (two times faster than Arrays.sort)

    public static void sort(int[] a, int from, int to) {
        int n = to - from;
        int[] temp = new int[n];
        int[] cnt = new int[1 << 16];
        for (int i = to - 1; i >= from; --i) {
            ++cnt[low(a[i])];
        }
        for (int i = 0; i < cnt.length - 1; ++i) {
            cnt[i + 1] += cnt[i];
        }
        for (int i = to - 1; i >= from; --i) {
            temp[--cnt[low(a[i])]] = a[i];
        }

        Arrays.fill(cnt, 0);
        for (int i = n - 1; i >= 0; --i) {
            ++cnt[high(temp[i])];
        }
        cnt[0] += from;
        for (int i = 0; i < cnt.length - 1; ++i) {
            cnt[i + 1] += cnt[i];
        }
        for (int i = n - 1; i >= 0; --i) {
            a[--cnt[high(temp[i])]] = temp[i];
        }
    }

    private static int high(int a) {
        return (a ^ Integer.MIN_VALUE) >>> 16;
    }

    private static int low(int a) {
        return a & 0xFFFF;
    }