heapsort(Java)(最小堆)

public static void main(String[] args)
{
    Scanner input = new Scanner(System.in);
    int n = input.nextInt();
    int[] a = new int[n];

    a[0] = 0;  //不使用第一个位置
    for(int i = 1; i < a.length; i++)
        a[i] = (int)(Math.random() * 100);
    //System.out.println(Arrays.toString(a));
    long start = System.currentTimeMillis();
    heapsort(a, a.length - 1);
    long end = System.currentTimeMillis();
    //System.out.println(Arrays.toString(a));
    System.out.println(end - start);
    //10000000个测试数据用时1050ms 100000000个测试数据用时11500ms
}

public void static heapsort(int[] a, int n)
{
    for(int i = n / 2; i >= 1; i--)
    sink(a, i, n);
    while(n > 1)
    {
    int temp = a[n];
    a[n--] = a[1];
    a[1] = temp;
    sink(a, 1, n);
    }
}

public static void sink(int[] a, int k, int n)  //最小堆化
{
    while(k <= n / 2)
    {
    int min_index = k * 2;
    if(min_index + 1 <= n && a[min_index + 1] < a[min_index])
        min_index++;
    if(a[k] > a[min_index])
    {
        int temp = a[k];
        a[k] = a[min_index];
        a[min_index] = temp;
        k = min_index;
    }
    else
        break;
    }
}