void selectSort(int A[], int lens)
{
    if (A == NULL || lens <=0)
        return;
    for (int i = 0; i < lens; ++i)
    {
        int minp = i;
        for (int j = i+1; j < lens; ++j)
        {
            if (A[j] < A[minp])
                minp = j;
        }
        swap(A[minp], A[i]);
    }
}