Question

我必须同时使用堆排序和快速排序，以便当递归深度超过原始列表大小的2的日志基数时，它会切换到堆排序实现。

我的堆排序功能：

import heapq

def heapSort(lst):
    """
    heapSort(List(Orderable)) -> List(Ordered)
        performs a heapsort on 'lst' returning a new sorted list
    Postcondition: the argument lst is not modified
    """
    heap = []
    for item in lst:
        heapq.heappush(heap, item)
    sortedlist = []
    while len(heap) > 0:
        sortedlist.append(heapq.heappop(heap))
    return sortedlist

我的快速排序功能：

def medianOf3(lst):
    """
    From a lst of unordered data, find and return the the median value from
    the first, middle and last values.
    """
    a,b,c = lst[0], lst[len(lst)//2], lst[-1]
    return min(min(max(a,b), max(b,c)), max(a,c))

def quickSort(lst):
    """
    quickSort: List(lst) -> List(result)
        Where the return 'result' is a totally ordered 'lst'.
        It uses the median-of-3 to select the pivot

    e.g.  quickSort([1,8,5,3,4]) == [1,3,4,5,8]
    """
    if lst == []:
        return []
    else:
        pivot = medianOf3(lst)
        less, same, more = partition(pivot, lst)
        return quickSort(less) + same + quickSort(more)

def partition( pivot, lst ):
   """
   partition: pivot (element in lst) * List(lst) -> 
        tuple(List(less), List(same, List(more))).  
   Where:
        List(Less) has values less than the pivot
        List(same) has pivot value/s, and
        List(more) has values greater than the pivot

   e.g. partition(5, [11,4,7,2,5,9,3]) == [4,2,3], [5], [11,7,9]
   """
   less, same, more = list(), list(), list()
   for val in lst:
       if val < pivot:
           less.append(val)
       elif val > pivot:
           more.append(val)
       else:
           same.append(val)
   return less, same, more

现在我尝试实现quipSort，以便在堆排序和快速排序之间切换：

def quipSortRec(lst, limit):
    """
    A non in-place, depth limited quickSort, using median-of-3 pivot.
    Once the limit drops to 0, it uses heapSort instead.
    """
    if limit <= 0:
        heapSort(lst)
    else:
        quickSort(lst)
        quipSortRec(lst, limit -1)

    return lst

def quipSort(lst):
    """
    The main routine called to do the sort.  It should call the
    recursive routine with the correct values in order to perform
    the sort
    """
    l = math.log2(len(lst))
    return quipSortRec(lst, l)

根本没有排序，我有点迷失了我的quipSort的错误。我的堆排序和快速排序表现不错。

Answer 1

您可以quipSortRec开始，但else应该看起来像quickSort的副本，其中递归调用现在调用quipSortRec。

一起使用heapsort和quicksort

1 个答案: