我正在撰寫一個函式，該函式遞回地查找二叉樹中的最小值和最大值并回傳一個元組 (min, max)。我的代碼為我的測驗用例回傳了正確的最小值和最大值，但分別回傳。任何有關如何讓它回傳元組的建議表示贊賞！（請注意，我不允許使用 LinkedBinaryTree 為我迭代樹的函式，但我附加了我當前在代碼下使用的類）
我的代碼
from LinkedBinaryTree import LinkedBinaryTree
def min_and_max(bin_tree):
if bin_tree is None:
raise Exception("Tree is empty")
def subtree_min_and_max(root):
minval = root.data
maxval = root.data
if (root.left is None and root.right is None):
temp = (minval, maxval)
return temp
elif (root.left is None):
ltemp = subtree_min_and_max(root.right)
if (ltemp[0] < minval):
minval= ltemp[0]
if (ltemp[1] > maxval):
maxval = ltemp[1]
temp = (minval, maxval)
return temp
elif (root.right is None):
subtree_min_and_max(root.left)
rtemp = subtree_min_and_max(root.right)
if (rtemp[0] < minval):
minval = rtemp[0]
if (rtemp[1] > maxval):
maxval = rtemp[1]
temp = (minval, maxval)
return temp
else:
ltemp = subtree_min_and_max(root.left)
rtemp = subtree_min_and_max(root.right)
print((min(root.data, ltemp[0], rtemp[0])))
print(max(root.data, ltemp[1], rtemp[1]))
temp = (min(root.data, ltemp[0], rtemp[0]), max(root.data, ltemp[1], rtemp[1]))
return temp
return subtree_min_and_max(bin_tree.root)
LinkedBinaryTree 類
from ArrayQueue import ArrayQueue
class LinkedBinaryTree:
class Node:
def __init__(self, data, left=None, right=None):
self.data = data
self.parent = None
self.left = left
if (self.left is not None):
self.left.parent = self
self.right = right
if (self.right is not None):
self.right.parent = self
def __init__(self, root=None):
self.root = root
self.size = self.count_nodes()
def __len__(self):
return self.size
def is_empty(self):
return len(self) == 0
def count_nodes(self):
def subtree_count(root):
if (root is None):
return 0
else:
left_count = subtree_count(root.left)
right_count = subtree_count(root.right)
return 1 left_count right_count
return subtree_count(self.root)
def sum(self):
def subtree_sum(root):
if (root is None):
return 0
else:
left_sum = subtree_sum(root.left)
right_sum = subtree_sum(root.right)
return root.data left_sum right_sum
return subtree_sum(self.root)
def height(self):
def subtree_height(root):
if (root.left is None and root.right is None):
return 0
elif (root.left is None):
return 1 subtree_height(root.right)
elif (root.right is None):
return 1 subtree_height(root.left)
else:
left_height = subtree_height(root.left)
right_height = subtree_height(root.right)
return 1 max(left_height, right_height)
if(self.is_empty()):
raise Exception("Tree is empty")
return subtree_height(self.root)
def preorder(self):
def subtree_preorder(root):
if (root is None):
pass
else:
yield root
yield from subtree_preorder(root.left)
yield from subtree_preorder(root.right)
yield from subtree_preorder(self.root)
def postorder(self):
def subtree_postorder(root):
if (root is None):
pass
else:
yield from subtree_postorder(root.left)
yield from subtree_postorder(root.right)
yield root
yield from subtree_postorder(self.root)
def inorder(self):
def subtree_inorder(root):
if (root is None):
pass
else:
yield from subtree_inorder(root.left)
yield root
yield from subtree_inorder(root.right)
yield from subtree_inorder(self.root)
def breadth_first(self):
if (self.is_empty()):
return
line = ArrayQueue()
line.enqueue(self.root)
while (line.is_empty() == False):
curr_node = line.dequeue()
yield curr_node
if (curr_node.left is not None):
line.enqueue(curr_node.left)
if (curr_node.right is not None):
line.enqueue(curr_node.right)
def __iter__(self):
for node in self.breadth_first():
yield node.data
我的測驗員代碼
root = LinkedBinaryTree.Node(3)
T = LinkedBinaryTree(root)
a = LinkedBinaryTree.Node(2)
a.parent = root
root.left = a
b = LinkedBinaryTree.Node(7)
b.parent = root
root.right = b
c = LinkedBinaryTree.Node(9)
c.parent = a
a.left = c
d = LinkedBinaryTree.Node(5)
d.parent = c
c.left = d
e = LinkedBinaryTree.Node(1)
e.parent = c
c.right = e
f = LinkedBinaryTree.Node(8)
f.parent = b
b.left = f
g = LinkedBinaryTree.Node(4)
g.parent = b
b.right = g
print(min_and_max(T))
測驗者代碼制作了一棵樹，看起來像
uj5u.com熱心網友回復：
在subtree_min_and_max, 情況下root.right is None，您的代碼執行以下操作：
subtree_min_and_max(root.left)
rtemp = subtree_min_and_max(root.right)
哪個應該是單
rtemp = subtree_min_and_max(root.left)
此時，子樹有空的右孩子，程式應該在左孩子中搜索 min 和 max。
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