[英]How can I sum all nodes under a given value in binary search tree?
我的作業需要我對BST中給定值下的所有數字求和。 但是,我不知道該怎么做。 感謝任何幫助。
class BinarySearchTree:
def __init__(self, data):
self.data = data
self.left = None
self.right = None
def search(self, find_data):
if self.data == find_data:
return self
elif find_data < self.data and self.left != None:
return self.left.search(find_data)
elif find_data > self.data and self.right != None:
return self.right.search(find_data)
else:
return None
def get_left(self):
return self.left
def get_right(self):
return self.right
def set_left(self, tree):
self.left = tree
def set_right(self, tree):
self.right = tree
def set_data(self, data):
self.data = data
def get_data(self):
return self.data
def create_new_bst(lst):
#creates a new tree with root node 55, and then inserts all the
#remaining values in order into the BST
def sum_beneath(t, value):
# don't know how to do
t = create_new_bst([55, 24, 8, 51, 25, 72, 78])
result = sum_beneath(t, 72)
print('Sum beneath 72 =', result)# should show 'Sum beneath 72 = 78'
我是BST的新手,所以我真的不知道如何開始和做這個問題。
def insert(self, new_data):#can I just call this function in 'create_new_bst'?
if self.data:
if new_data < self.data:
if self.left is None:
self.left = BinarySearchTree(new_data)
else:
self.left.insert(new_data)
elif new_data > self.data:
if self.right is None:
self.right = BinarySearchTree(new_data)
else:
self.right.insert(new_data)
else:
self.data = data
好的,因為這是一個練習,所以我不會填寫所有內容,但是我會盡力讓您了解應該如何做:
您需要以一種簡單的方法來創建樹:
def create_new_bst(lst):
tree = BinarySearchTree(tree[0])
# And then, using the insert method, which is correct, add your nodes in the tree
return tree
首先,您需要找到根目錄為72
子樹
# Replace the pass with the appropriate code
def find_subtree(tree, value):
if value == tree.data: # This is found yeah !
pass
if value > tree.data: # Ok, this is not our data, we should look recursively in one of the children (I will not tell you which one). Maybe we can use find_subtree reccursively?
pass
if value < tree.data: # Same as above, but maybe we should look in the other child
pass
raise ValueError("Not found value " + str(value)) # Nothing has been found.
現在,您使用my_tree = find_subtree(t, 72)
找到了樹,您應該將左樹(如果存在)和右樹(如果存在)相加
def sum_beneath(t, value):
my_tree = find_subtree(t, value)
s = 0
if my_tree.left is not None:
s += my_tree.left.sum_tree()
if my_tree.right is not None:
s += my_tree.right.sum_tree()
return s
讓我們定義sum_tree
方法(在類中)! :)
def sum_tree(self):
ans = self.data
# Add the left sum reccursively
# Add the right sum reccursively
return ans
我希望這將幫助您理解BST的概念。 如果您需要幫助,請隨時評論
找到特定值下的節點總和是一個非常有趣的問題,我們可以想到諸如搜索和穿越問題之類的東西,可以有多種方式來實現,但是我可以想到這樣的事-
我能想到的O時間復雜度應該是這樣的-
對於BST中的第n個節點, log(n)應該是搜索時間,對於橫向(按順序,按后順序或按順序),應該為mn ,其中(m是節點)
因此,總數為(log(n)+ m-n)〜O(M)。
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