Quicksort（简单到位）

Question

我实施了QuickSort（简单和就地）策略。我了解到In Place排序技术必须比Simple QuickSort更快，但我尝试了3次随机数组，阵列大小为2,000,000，Simple QuickSort更快。

我的In Place实施是否错误？

简单的QuickSort代码：

def quick(arr):
    if (len(arr) > 1):
        less = []
        equal = []
        greater = []

        pivot = arr[0]
        for i in arr:
            if (i < pivot):
                less.append(i)
            elif (i == pivot):
                equal.append(i)
            else:
                greater.append(i)
        return quick(less) + equal + quick(greater)
    else:
        return arr

就地QS代码：

def quickSort(arr, leftIndex = 0, rightIndex = None):
    if (rightIndex is None):
        rightIndex = len(arr) - 1

    def _partition(arr, leftIndex, rightIndex):
        pivot = arr[int((leftIndex + rightIndex)/2)]
        while(leftIndex <= rightIndex):
            while (arr[leftIndex] < pivot):
                leftIndex += 1
            while (arr[rightIndex] > pivot):
                rightIndex -= 1
            if (leftIndex <= rightIndex):
                temp = arr[leftIndex]
                arr[leftIndex] = arr[rightIndex]
                arr[rightIndex] = temp
                leftIndex += 1
                rightIndex -= 1
        return leftIndex

    def _quickSort(arr, leftIndex, rightIndex):
        index = _partition(arr, leftIndex, rightIndex)
        if (leftIndex < index - 1):
            _quickSort(arr, leftIndex, index - 1)
        if (index < rightIndex):
            _quickSort(arr, index, rightIndex)

    _quickSort(arr, leftIndex, rightIndex)

主

randomArr = numpy.random.randint(low=-999999, high=9999999, size=2000000)

start = time.time()
quickArr = quick(randomArr)
print("----Quick (Simple): %.2f seconds----" % float(time.time() - start))

start = time.time()
quickSort(randomArr)
print("----Quick (In Place): %.2f seconds----" % float(time.time() - start))

输出：

Trial 1:
----Quick (Simple): 13.08 seconds----                                                      
----Quick (In Place): 17.24 seconds----

Trial 2:
----Quick (Simple): 14.25 seconds----                                                                        
----Quick (In Place): 18.50 seconds----

Trial 3:
----Quick (Simple): 12.94 seconds----                                         
----Quick (In Place): 17.32 seconds----