錯誤輸出

Question

我寫了下面的堆排序的代碼堆排序（用Python編寫的），我得到錯誤的輸出（未排序）的時間，我似乎無法找到爲什麼...任何幫助將是非常感激！

def heap_sort(self, a): 

    heapsize = self.build_max_heap(a) 

    n = len(a)-1 
    i = len(a)-1 

    for i in range(i, 0, -1): 
     temp = a[0] 
     a[0] = a[i] 
     a[i] = temp 
     heapsize = heapsize - 1 
     self.max_heapify(heapsize, a, 0)  #rebuild max heap at with new root 

    return a 

def max_heapify(self, heapsize, a, i): 

    left = (2*(i+1))-1  #left child of i 
    right = 2*(i+1)    #right child of i 
    largest = i 

    if left < heapsize and a[left] > a[i]: 
     largest = left 

    if right < heapsize and a[right] > a[largest]: 
     largest = right 

    if largest != i: 
     temp = a[largest] 
     a[largest] = a[i] 
     a[i] = temp 
     self.max_heapify(heapsize, a, largest) 

def build_max_heap(self, a): 

    heapsize = len(a) 
    i = int(heapsize/2)-1 

    for i in range(i, 0): 
     self.max_heapify(heapsize, a, i) 

    return heapsize 

我的測試：

#--Test for 0 in array--# 
def zero_array(self): 
    a = [12,0,232] 
    print self.sort.heap_sort(a) 
    return 

#--Test for duplicate in array--# 
def duplicate_array(self): 
    a = [12, 12, 7] 
    print self.sort.heap_sort(a) 
    return 

#--Test for all same values in array--# 
def allsame_array(self): 
    a = [1,1,1] 
    print self.sort.heap_sort(a) 
    return 

#--Test for negative values in array--# 
def negative_array(self): 
    a = [-23, -2, 123] 
    print self.sort.heap_sort(a) 
    return 

輸出（這是應該的所有排序）：

[0, 232, 12] 
    [7, 12, 12] 
    [1, 1, 1] 
    [-2, 123, -23] 

Answer 1

這可能是因爲你的第二個range()是增加而不是向前倒着。

for i in range(i, 0): 

應該是：

for i in range(i, 0, -1): 

你還需要記住，range()將只是第二個參數之前停止，所以range(5, 0, -1)將返回[5, 4, 3, 2, 1]。