java实现希尔排序

public static void main(String[] args) {
    Comparable[] a = {23, 3, 4, 5, 30, 2};
    sort(a);
    show(a);
}
//algorith
public static void sort(Comparable[] a){
    int N = a.length;
    int h = 1;
    while (h < N/3) h = 3*h + 1;
    while (h >= 1){
        for (int i = h; i < N; i++){
            for (int j = i; j >=h && less(a[j], a[j-h]); j -= h)
                exch(a, j, j-h);
        }
        h = h/3;
    }
}

private static boolean less(Comparable v, Comparable w){ return v.compareTo(w) < 0;}
private static void exch(Comparable[] a, int i, int j){
    Comparable t = a[i]; a[i] = a[j]; a[j] = t;
}
private static void show(Comparable[] a){
    for (int i = 0; i < a.length; i++)
        System.out.print(a[i] + " ");
    System.out.println();
}
public static boolean isSorted(Comparable[] a){
    for (int i = 1; i < a.length; i++)
        if (less(a[i], a[i-1]))
            return false;
    return true;
}