我刚刚在python中创建了一个堆类，我仍在使用Tree遍历。当我调用None is not in the list时，我收到错误left。在我的三个遍历函数中，它们都需要right和class myHeap:
heapArray = []
def __init_(self):
self.heapArray = []
def __str__(self):
string = " ".join(str(x) for x in self.heapArray)
return string
def makenull(self):
self.heapArray = []
def insert(self, x):
self.heapArray.append(x)
self.upheap(self.heapArray.index(x))
def parent(self, i):
p = (i - 1) / 2
p = int(p)
if(p >= 0):
return self.heapArray[p]
else:
return None
def left(self, i):
l = (i + 1) * 2 - 1
l = int(l)
if(l < len(self.heapArray)):
return self.heapArray[l]
else:
return
def right(self, i):
r = (i + 1) * 2
r = int(r)
if(r < len(self.heapArray)):
return self.heapArray[r]
else:
return None
def swap(self, a, b):
temp = self.heapArray[a]
self.heapArray[a] = self.heapArray[b]
self.heapArray[b] = temp
def upheap(self, i):
if(self.parent(i) and self.heapArray[i] < self.parent(i)):
p = (i - 1) / 2
p = int(p)
self.swap(i, p)
i = p
self.upheap(i)
else:
return
def downheap(self, i):
if(self.left(i) and self.right(i)):
if(self.left(i) <= self.right(i)):
n = self.heapArray.index(self.left(i))
self.swap(i, n)
self.downheap(n)
else:
n = self.heapArray.index(self.right(i))
self.swap(i, n)
self.downheap(n)
elif(self.left(i)):
n = self.heapArray.index(self.left(i))
self.swap(i, n)
self.downheap(n)
elif(self.right(i)):
n = self.heapArray.index(self.right())
self.swap(i,n)
self.downheap(n)
else:
return
def inorder(self, i):
if(self.heapArray[i] != None):
self.inorder(self.heapArray.index(self.left(i)))
print(self.heapArray[i], end=" ")
self.inorder(self.heapArray.index(self.right(i)))
def preorder(self, i):
if(self.heapArray[i] != None):
print(self.heapArray[i], end=" ")
self.preorder(self.heapArray.index(self.left(i)))
self.preorder(self.heapArray.index(self.right(i)))
def postorder(self, i):
if(self.heapArray[i]!= None):
self.postorder(self.heapArray.index(self.left(i)))
self.postorder(self.heapArray.index(self.right(i)))
print(self.heapArray[i], end=" ")
def min(self):
return self.heapArray[0]
def deletemin(self):
self.swap(0, len(self.heapArray) - 1)
self.heapArray.pop
self.downheap(0)
def main():
heap = myHeap()
heap.insert(0)
heap.insert(15)
heap.insert(7)
heap.insert(8)
heap.insert(1)
heap.insert(2)
heap.insert(22)
print(heap)
print(heap.heapArray[0])
heap.inorder(0)
heap.preorder(0)
heap.postorder(0)
if __name__ == "__main__":
main()
函数。我认为问题出在这两个函数中，但我不知道如何修复它。
IN答案 0 :(得分：0)
当你将树跟随其左边的孩子，并且没有左孩子时，那么你应该完成那条路径。你保证最终会得到无左子，这应该是你结束递归的基本情况。
相反，您查找左子项的值（使用其索引），然后反向计算您已从该值中获得的索引（希望没有重复项）。由于最终会有无左子，当你尝试反向计算无索引时，你会发现“self.heapArray”中没有None并且得到了确切的错误“None not not in list”
答案 1 :(得分：0)
想象一下当您在叶节点上调用inorder时会发生什么。它进入if语句的主体并尝试获取叶子节点的左右子节点 - 但是没有子节点 - 所以当self.left(i)求值为None并且被馈送到{{1 }} 方法。您需要修改结束递归的方式，以检查节点是否有左右子节点。