Given a Binary Tree and a target key, you need to find all the ancestors of the given target key.
              1
            /   \
          2      3
        /  \
      4     5
     /
    7
Key: 7
Ancestor: 4 2 1
Example 1:
Input:
        1
      /   \
     2     3
target = 2
Output: 1
Example 2:
Input:
         1
       /   \
      2     3
    /  \   /  \
   4    5 6    8
  /
 7
target = 7
Output: 4 2 1
Your Task:
Your task is to complete the function Ancestors() that finds all the ancestors of the key in the given binary tree.
Note:
The return type is
cpp: vector
Java: ArrayList
python: list
Expected Time Complexity: O(N).
Expected Auxiliary Space: O(H).
Note: H is the height of the tree and this space is used implicitly for the recursion stack.
Constraints:
1 ≤ N ≤ 10^{3}
1 ≤ data of node ≤ 10^{4}

Source: geeksforgeeks | Difficulty: EASY
Tags: Tree algorithms

Data structures

Starter code: #User function Template for python3



'''

# Node Class:

class Node:

    def __init__(self,val):

        self.data = val

        self.left = None

        self.right = None

'''

class Solution:

    def Ancestors(self, root,target):

        '''

        :param root: root of the given tree.

        :return: None, print the space separated post ancestors of given target., don't print new line

        '''

        #code here

  

Solutions:
class Solution:

	def Ancestors(self, root, target):

		def ansc(root, t, ans):
			if root == None:
				return False
			if root.data == t:
				return True
			if ansc(root.left, t, ans) or ansc(root.right, t, ans):
				ans.append(root.data)
				return True
		ans = []
		ansc(root, target, ans)
		return ans


class Solution:

	def Ancestors(self, root, target):
		ans = []

		def solve(root, k, ans):
			if root == None:
				return False
			if root.data == k:
				return True
			if solve(root.left, k, ans) or solve(root.right, k, ans):
				ans.append(root.data)
				return True
		solve(root, target, ans)
		return ans


def slove(root, target, ans):
	if root is None:
		return False
	if root.data == target:
		return True
	if slove(root.left, target, ans) or slove(root.right, target, ans):
		ans.append(root.data)
		return True
	return False

class Solution:

	def Ancestors(self, root, target):
		ans = []
		slove(root, target, ans)
		return ans


def ancesstor(root, path, target):
	if root == None:
		return False
	path.append(root.data)
	if root.data == target:
		return True
	if ancesstor(root.left, path, target) or ancesstor(root.right, path, target):
		return True
	path.pop(-1)
	return False

class Solution:

	def Ancestors(self, root, target):
		path = []
		ancesstor(root, path, target)
		path.pop()
		path.reverse()
		return path


class Solution:

	def Ancestors(self, root, target):
		arr = []

		def ans(root):
			if not root:
				return False
			if root.data == target:
				return True
			ls = ans(root.left)
			if ls:
				arr.append(root.data)
				return True
			rs = ans(root.right)
			if rs:
				arr.append(root.data)
				return True
			return False
		ans(root)
		return arr


class Solution:

	def Ancestors(self, root, target):
		R = []

		def rec(root, target):
			if root.data == target:
				return True
			(t1, t2) = (False, False)
			if root.left:
				t1 = rec(root.left, target)
			if root.right:
				t2 = rec(root.right, target)
			if t1 or t2:
				R.append(root.data)
				return True
			return False
		rec(root, target)
		return R


class Solution:

	def Ancestors(self, root, target):
		if root == None:
			return []
		l = []

		def helper(root, l):
			if root != None:
				if root.data == target:
					return 1
				if helper(root.left, l) or helper(root.right, l):
					l.append(root.data)
					return 1
			if root == None:
				return 0
		helper(root, l)
		return l


class Solution:

	def fun(self, root, l, target, res):
		if root == None:
			return
		if root.data == target:
			res.extend(l)
		l.append(root.data)
		self.fun(root.left, l, target, res)
		self.fun(root.right, l, target, res)
		l.pop()

	def Ancestors(self, root, target):
		(l, res) = ([], [])
		self.fun(root, l, target, res)
		res = res[::-1]
		return res


class Solution:

	def Ancestors(self, root, target):
		result = []
		self.recursiveFindParent(root, target, result)
		return result

	def recursiveFindParent(self, root, target, result):
		if not root:
			return None
		if root.data == target:
			return root
		if self.recursiveFindParent(root.left, target, result) or self.recursiveFindParent(root.right, target, result):
			result.append(root.data)
			return root
		else:
			return None


class Solution:

	def solve(self, root, ans, target, out):
		if root == None:
			return
		if root.data == target:
			ans += out.copy()
			return
		out.append(root.data)
		self.solve(root.left, ans, target, out)
		self.solve(root.right, ans, target, out)
		out.pop(-1)

	def Ancestors(self, root, target):
		ans = []
		self.solve(root, ans, target, [])
		return ans[::-1]


class Solution:

	def Ancestors(self, root, target):
		stack = []
		stack.append([root, root])
		ans = None
		while stack:
			node = stack.pop()
			if node[0].data == target:
				ans = node
				break
			if node[0].left:
				stack.append([node[0].left, node])
			if node[0].right:
				stack.append([node[0].right, node])
		some = 0
		res = []
		while some != root:
			ans = ans[1]
			some = ans[0]
			res.append(some.data)
		return res


class Solution:

	def Ancestors(self, root, target):

		def pathtonode(root, k, p1):
			if root == None:
				return False
			if root.data == k:
				return True
			p1.append(root.data)
			if root.left and pathtonode(root.left, k, p1) or (root.right and pathtonode(root.right, k, p1)):
				return True
			p1.pop()
		p1 = []
		pathtonode(root, target, p1)
		p1.reverse()
		return p1


class Solution:

	def Ancestors(self, root, target):
		self.val = []

		def t(rt, tar, va):
			if not rt:
				return 0
			if rt.data == tar:
				return 1
			if t(rt.left, tar, va) or t(rt.right, tar, va):
				va.append(rt.data)
				return 1
			return 0
		t(root, target, self.val)
		return self.val


class Solution:

	def find_root_to_node(self, current, node, result):
		if not current:
			return False
		if current:
			result.append(current.data)
			if current.data == node:
				return True
			if self.find_root_to_node(current.left, node, result) == True:
				return True
			if self.find_root_to_node(current.right, node, result) == True:
				return True
			result.pop(-1)

	def Ancestors(self, root, target):
		res = []
		self.find_root_to_node(root, target, res)
		return res[0:len(res) - 1][::-1]


class Solution:

	def Ancestors(self, root, target):
		self.ans = []

		def solve(root, n):
			if root == None:
				return False
			if root.data == n:
				return True
			l = solve(root.left, n)
			r = solve(root.right, n)
			if l or r:
				self.ans.append(root.data)
			if l:
				return l
			return r
		solve(root, target)
		return self.ans


class Solution:

	def Ancestors(self, root, target):
		arr = []
		self._ancestors(root, target, arr)
		return arr

	def _ancestors(self, node, target, arr):
		if node is None:
			return False
		if node.data == target:
			return True
		elif self._ancestors(node.left, target, arr) == True:
			arr.append(node.data)
			return True
		elif self._ancestors(node.right, target, arr) == True:
			arr.append(node.data)
			return True


class Solution:

	def getT(self, root, target, arr):
		if not root:
			return False
		if root.data == target:
			return True
		if self.getT(root.left, target, arr) or self.getT(root.right, target, arr):
			arr.append(root.data)
			return True
		return False

	def Ancestors(self, root, target):
		arr = []
		bl = self.getT(root, target, arr)
		return arr


class Solution:

	def Ancestors(self, root, target):

		def helper(root):
			if not root:
				return False
			if root.data == target:
				return True
			left = helper(root.left)
			right = helper(root.right)
			if left or right:
				print(root.data, end=' ')
				return True
		helper(root)
		return []


class Solution:

	def Ancestors(self, root, target):
		stack = [root]
		parents = {}
		parents[root.data] = None
		while len(stack) > 0:
			current = stack.pop()
			if current.data == target:
				ancestors = []
				while parents[target]:
					ancestors.append(parents[target])
					target = parents[target]
				return ancestors
			if current.left:
				parents[current.left.data] = current.data
				stack.append(current.left)
			if current.right:
				parents[current.right.data] = current.data
				stack.append(current.right)
		return None


class Solution:

	def Ancestors(self, root, target):
		sol = []

		def printAns(root):
			if root == None:
				return None
			if root.data == target:
				return root
			l = printAns(root.left)
			r = printAns(root.right)
			if l or r:
				sol.append(root.data)
			return l if l else r
		val = printAns(root)
		return sol


class Solution:

	def Ancestors(self, root, target):
		list = []

		def find_ans(root, target, list):
			if not root:
				return False
			if root.data == target:
				return True
			list.append(root.data)
			left = find_ans(root.left, target, list)
			right = find_ans(root.right, target, list)
			if left or right:
				return True
			list.pop()
		find_ans(root, target, list)
		return list[::-1]


class Solution:

	def Ancestors(self, root, target):
		res = []

		def helper(root):
			if not root:
				return False
			if root.data == target:
				return True
			if helper(root.left) or helper(root.right):
				res.append(root.data)
				return True
		helper(root)
		return res


class Solution:

	def Ancestors(self, root, target):
		if root == None:
			return
		v = []
		self.helper(root, target, v)
		return v

	def helper(self, root, x, v):
		if root == None:
			return
		left = self.helper(root.left, x, v)
		right = self.helper(root.right, x, v)
		if left or right:
			v.append(root.data)
			return True
		if root.data == x:
			return True
		return False


class Solution:

	def __init__(self):
		self.ans = []

	def dfs(self, root, target):
		if root is None:
			return False
		if root.data == target:
			return True
		l = self.dfs(root.left, target)
		r = self.dfs(root.right, target)
		if l is True or r is True:
			self.ans.append(root.data)
			return True
		return False

	def Ancestors(self, root, target):
		self.ans = []
		if root.data == target:
			return []
		self.dfs(root, target)
		return self.ans


import sys
sys.setrecursionlimit(10 ** 6)

class Solution:

	def Ancestors(self, root, target):
		array = []

		def Recursion(root, target):
			nonlocal array
			if root == None:
				return False
			if root.data == target:
				return True
			left_tree = Recursion(root.left, target)
			right_tree = Recursion(root.right, target)
			if left_tree == True or right_tree == True:
				array.append(root.data)
			return left_tree or right_tree
		Recursion(root, target)
		return array


def has(root):
	m = {}
	q = []
	q.append(root)
	while q:
		temp = q.pop()
		if temp.left:
			m[temp.left.data] = temp.data
			q.append(temp.left)
		if temp.right:
			m[temp.right.data] = temp.data
			q.append(temp.right)
	return m

class Solution:

	def Ancestors(self, root, target):
		m = has(root)
		res = []
		while True:
			if target in m:
				res.append(m[target])
				target = m[target]
			else:
				break
		return res


class Solution:

	def get_all_ancestors(self, root, target, ancestors):
		if root == None:
			return
		if root.data == target:
			return True
		left_ans = self.get_all_ancestors(root.left, target, ancestors)
		right_ans = self.get_all_ancestors(root.right, target, ancestors)
		if left_ans or right_ans:
			ancestors.append(root.data)
			return True
		else:
			return False

	def Ancestors(self, root, target):
		ancestors = []
		self.get_all_ancestors(root, target, ancestors)
		return ancestors


class Solution:

	def Ancestors(self, root, target):
		res = []

		def helper(root):
			if not root:
				return 0
			if root.data == target:
				return 1
			if helper(root.left) or helper(root.right):
				res.append(root.data)
				return 1
			return 0
		helper(root)
		return res


class Solution:

	def add_nodes(self, root, target):
		if not root:
			return False
		if root.data == target:
			return True
		if self.add_nodes(root.left, target) or self.add_nodes(root.right, target):
			self.ans.append(root.data)
			return True
		return False

	def Ancestors(self, root, target):
		self.ans = []
		self.add_nodes(root, target)
		return self.ans


class Solution:

	def Ancestors(self, root, target):
		result = []
		self.Utils(root, target, result)
		return result[::-1]

	def Utils(self, node, target, result):
		if not node:
			return False
		if node.data == target:
			return True
		result.append(node.data)
		l = self.Utils(node.left, target, result)
		r = self.Utils(node.right, target, result)
		if not (l or r):
			result.pop()
		return l or r


class Solution:

	def __init__(self):
		self.l1 = []

	def Ancestors(self, root, target):
		self.solve(root, target, [])
		return self.l1

	def solve(self, root, t, l):
		if root == None:
			return
		if root.data == t:
			self.l1 = l.copy()
			return
		self.solve(root.left, t, [root.data] + l)
		self.solve(root.right, t, [root.data] + l)


class Solution:

	def solve(self, root, arr, target):
		if not root:
			return False
		elif root.data == target:
			return True
		if self.solve(root.left, arr, target):
			arr.append(root.data)
			return True
		if self.solve(root.right, arr, target):
			arr.append(root.data)
			return True
		return False

	def Ancestors(self, root, target):
		arr = []
		self.solve(root, arr, target)
		return arr


class Solution:

	def recur(self, root, target, res):
		if root == None:
			return
		res.append(root.data)
		if root.data == target:
			return True
		lh = self.recur(root.left, target, res)
		rh = self.recur(root.right, target, res)
		if lh == None and rh == None:
			res.pop()
			return
		elif lh == True or rh == True:
			return True
		else:
			return

	def Ancestors(self, root, target):
		res = []
		self.recur(root, target, res)
		res.reverse()
		res.pop(0)
		return res


class Solution:

	def Ancestors(self, root, target):
		ancestor = []

		def finder(root):
			if root == None:
				return
			if root.data == target:
				return True
			ancestor.append(root.data)
			if finder(root.left):
				return True
			if finder(root.right):
				return True
			ancestor.pop()
		finder(root)
		return reversed(ancestor)


xx = 0

class Solution:

	def Ancestors(self, root, target):
		Z = []
		self.kthAncestor(root, target, Z)
		return Z

	def size(self, root, e):
		global xx
		if root is None:
			return
		self.size(root.left, e)
		if root.data > xx:
			xx = root.data
		self.size(root.right, e)

	def kthAncestor(self, root, nod, Z):
		global xx
		e = []
		self.size(root, e)
		n = xx
		if root is None:
			return -1
		A = []
		C = []
		B = []
		D = []
		A.append(root)
		ancestors = [0] * (n + 1)
		ancestors[root.data] = -1
		while len(A) > 0:
			while len(A) > 0:
				node = A.pop(0)
				B.append(node.data)
				if node.left is not None:
					ancestors[node.left.data] = node.data
					D.append(node.left)
				if node.right is not None:
					ancestors[node.right.data] = node.data
					D.append(node.right)
			A.extend(D)
			D = []
			C.append(B)
			B = []
		g = nod
		while 1:
			x = ancestors[g]
			if x == -1:
				break
			g = x
			Z.append(x)


class Solution:

	def Ancestors(self, root, target):

		def dfs(node, subset):
			if not node:
				return None
			if node.data == target:
				return subset
			return dfs(node.left, subset + [node.data]) or dfs(node.right, subset + [node.data])
		res = dfs(root, [])
		if res:
			return res[::-1]
		return []


class Solution:

	def Ancestors(self, root, target):
		ans = []
		dfs(root, target, ans)
		return ans

def dfs(n, t, ans):
	if not n:
		return False
	l = dfs(n.left, t, ans)
	r = dfs(n.right, t, ans)
	if l or r:
		ans.append(n.data)
		return True
	if n.data == t:
		return True
	return False


class Solution:

	def Ancestors(self, root, target):
		dic = {}
		ans = {root.data: -1}
		q = deque()
		q.append(root)
		l = 1
		while q:
			for i in range(len(q)):
				node = q.popleft()
				if node.left:
					q.append(node.left)
					ans[node.left.data] = node.data
				if node.right:
					q.append(node.right)
					ans[node.right.data] = node.data
				dic[node.data] = l
			l += 1
		res = []
		d = dic[target]
		for i in range(d - 1):
			k = ans[target]
			target = k
			res.append(k)
		return res


class Node:

	def __init__(self, val):
		self.data = val
		self.left = None
		self.right = None

class Solution:

	def Ancestors(self, root, target):
		if root == None:
			return None
		if root.data == target:
			return []
		left = self.Ancestors(root.left, target)
		right = self.Ancestors(root.right, target)
		if left != None and right != None:
			return [*left, root.data, *right]
		elif left != None:
			return [*left, root.data]
		elif right != None:
			return [*right, root.data]
		else:
			return None


class Solution:

	def __init__(self):
		self.result = []

	def Ancestors(self, root, target):
		us = {}
		q = []
		if root is None:
			return []
		q.append(root)
		while len(q) > 0:
			t = q.pop(0)
			if t.data == target:
				self.result.append(root.data)
				self.print_path(us, root, t)
				self.result = self.result[::-1]
				self.result.pop(0)
				return self.result
			if t.left is not None and t.left not in us:
				us[t.left] = t
				q.append(t.left)
			if t.right is not None and t.right not in us:
				us[t.right] = t
				q.append(t.right)

	def print_path(self, f, root, target):
		if target not in f:
			return
		else:
			self.print_path(f, root, f[target])
			self.result.append(target.data)


class Solution:

	def Ancestors(self, root, target):
		list = []
		node = []
		self.Travel(root, target, list, node)
		return list[::-1]

	def Travel(self, root, target, list, node):
		if root != None:
			if root.data == target:
				for i in node:
					list.append(i)
				return
			node.append(root.data)
			self.Travel(root.left, target, list, node)
			self.Travel(root.right, target, list, node)
			node.remove(root.data)


class Solution:

	def Ancestors(self, root, target):
		return self.myFunc(root, [], target, 0)[::-1]

	def myFunc(self, root, path, key, level):
		if not root:
			return []
		if root.data == key:
			return path.copy()
		level += 1
		path.append(root.data)
		left = self.myFunc(root.left, path, key, level)
		path = path[:level]
		right = self.myFunc(root.right, path, key, level)
		return left + right


class Solution:

	def Ancestors(self, root, target):
		ans = list()

		def ancest(root, target, res):
			if root == None:
				return False
			if root.data == target:
				return True
			if ancest(root.left, target, res) or ancest(root.right, target, res):
				res.append(root.data)
				return True
			return False
		ancest(root, target, ans)
		return ans


class Solution:

	def set_parent(self, root, parent):
		stack = []
		stack.append(root)
		while stack:
			cur = stack.pop()
			if cur.right:
				parent[cur.right.data] = cur.data
				stack.append(cur.right)
			if cur.left:
				parent[cur.left.data] = cur.data
				stack.append(cur.left)

	def rootToLeaf(self, parent, target):
		ans = []
		k = target
		while k != 0:
			k = parent[k]
			if k != 0:
				ans.append(k)
		return ans

	def Ancestors(self, root, target):
		parent = {}
		parent[root.data] = 0
		self.set_parent(root, parent)
		return self.rootToLeaf(parent, target)


class Solution:

	def Ancestors(self, root, target):

		def parent(root):
			if root == None:
				return None
			if root.left:
				dict1[root.left.data] = root.data
			if root.right:
				dict1[root.right.data] = root.data
			if root.left:
				parent(root.left)
			if root.right:
				parent(root.right)
		dict1 = {root.data: -1}
		parent(root)
		node = target
		list1 = []
		while node != -1:
			node = dict1[node]
			if node == -1:
				break
			list1.append(node)
		return list1


class Solution:

	def Ancestors(self, node, target):
		arr = []

		def solve(root, n, arr):
			if root is None:
				return False
			if root.data == n:
				return True
			left = solve(root.left, n, arr)
			right = solve(root.right, n, arr)
			if left or right:
				arr.append(root.data)
				return True
		solve(node, target, arr)
		return arr


class Solution:

	def Ancestors(self, root, target):
		l = []
		if self.findAncestors(root, target, l):
			return l
		else:
			return l

	def findAncestors(self, root, target, l):
		if root == None:
			return False
		if root.data == target:
			return True
		if self.findAncestors(root.left, target, l) or self.findAncestors(root.right, target, l):
			l.append(root.data)
			return True


class Solution:

	def Ancestors(self, root, target):
		res = []
		self.fun(root, res)
		return res[::-1]

	def fun(self, root, res):
		if root is None:
			return
		if root.data == target:
			return 1
		res.append(root.data)
		a1 = self.fun(root.left, res)
		if a1 == 1:
			return 1
		a2 = self.fun(root.right, res)
		if a2 == 1:
			return 1
		res.pop()


class Solution:

	def Ancestors(self, root, target):

		def ancestors(root, target):
			nonlocal cur, res
			if root is None or len(res) != 0:
				return
			if root.data == target:
				res = cur[:]
				return
			cur.append(root.data)
			ancestors(root.left, target)
			ancestors(root.right, target)
			cur.pop()
			return
		(cur, res) = ([], [])
		ancestors(root, target)
		res.reverse()
		return res


class Solution:

	def Ancestors(self, root, target):
		if root is None:
			return []
		arr = []
		self.AncestorsUtil(root, target, arr)
		return arr

	def AncestorsUtil(self, root, target, nodes):
		if root == None:
			return False
		if root.data == target:
			return True
		if self.AncestorsUtil(root.left, target, nodes) or self.AncestorsUtil(root.right, target, nodes):
			nodes.append(root.data)
			return True
		return False


class Solution:

	def Ancestors(self, root, target):
		d = {}
		l = []
		if not root:
			return
		self.helper(root, d)
		m = d[target]
		while m in d:
			l.append(m)
			m1 = d[m]
			m = m1
		l.append(m)
		return l

	def helper(self, root, d):
		if not root:
			return
		if root.left:
			d[root.left.data] = root.data
			self.helper(root.left, d)
		if root.right:
			d[root.right.data] = root.data
			self.helper(root.right, d)


class Solution:

	def find_ancestors(self, root, target, res):
		if root is None:
			return False
		if self.find_ancestors(root.left, target, res) or self.find_ancestors(root.right, target, res):
			res.append(root.data)
			return True
		if root.data == target:
			return True
		return False

	def Ancestors(self, root, target):
		res = []
		self.find_ancestors(root, target, res)
		return res


class Solution:

	def __init__(self):
		self.arr = []

	def dfs(self, root, target):
		if root == None:
			return False
		if root.data == target:
			return True
		if self.dfs(root.left, target) or self.dfs(root.right, target):
			self.arr.append(root.data)
			return True
		return False

	def Ancestors(self, root, target):
		self.dfs(root, target)
		return self.arr


class Solution:

	def __init__(self):
		self.ancestors_list = []

	def Ancestors(self, root, target):
		self.find_ancestors(root, target)
		return self.ancestors_list

	def find_ancestors(self, node, target):
		if node == None:
			return False
		if node.data == target:
			return True
		r_target = self.find_ancestors(node.right, target)
		l_target = self.find_ancestors(node.left, target)
		if r_target or l_target:
			self.ancestors_list.append(node.data)
			return True


class Solution:

	def Ancestors(self, root, target):
		ans = []

		def recurs(root, target):
			if root.data == target:
				return True
			else:
				p = False
				q = False
				if root.left:
					p = recurs(root.left, target)
				if root.right:
					q = recurs(root.right, target)
				if p or q:
					ans.append(root.data)
					return True
				return False
		recurs(root, target)
		return ans


class Solution:

	def Ancestors(self, root, target):

		def helper(root, res, target):
			if not root:
				return
			if root.data == target:
				return res
			x = helper(root.left, res + [root.data], target)
			if x:
				return x
			y = helper(root.right, res + [root.data], target)
			if y:
				return y
		res = helper(root, [], target)
		return res[::-1]


class Solution:

	def getPath(self, root, data, result):
		if root:
			result.append(root.data)
			if self.getPath(root.left, data, result):
				return result
			if self.getPath(root.right, data, result):
				return result
			if root.data == data:
				return result
			result.pop()

	def Ancestors(self, root, target):
		result = []
		self.getPath(root, target, result)
		mainResult = []
		for i in range(len(result) - 2, -1, -1):
			mainResult.append(result[i])
		return mainResult


class Solution:

	def Ancestors(self, root, target):
		(arr1, arr2) = ([], [])
		flag = [0, 0]
		arr1 = self.first(root, target, arr1, flag)
		arr = arr1[0:len(arr1) - 1]
		return arr[::-1]

	def first(self, root, n1, arr1, flag):
		if root is None:
			return 0
		if flag[0] == 0:
			if root.data == n1:
				flag[0] = 1
			arr1.append(root.data)
		self.first(root.left, n1, arr1, flag)
		self.first(root.right, n1, arr1, flag)
		if flag[0] == 0:
			arr1.pop()
		return arr1


class Solution:

	def Ancestors(self, root, target):
		x = []

		def helper(root, target):
			if not root:
				return False
			if root.data == target:
				return True
			l = helper(root.left, target)
			r = helper(root.right, target)
			if l == True or r == True:
				x.append(root.data)
				return True
			return False
		helper(root, target)
		return x


class Solution:

	def Ancestors(self, root, target):
		self.lst = []
		self.f = 0

		def dfs(root, target):
			if not root:
				return
			if root.data == target:
				self.f = 1
				return
			if self.f == 0:
				self.lst.append(root.data)
			dfs(root.left, target)
			dfs(root.right, target)
			if self.f != 1:
				self.lst.pop()
		dfs(root, target)
		return self.lst[::-1]


class Solution:

	def Ancestors(self, root, target):

		def bfs(root, d):
			q = [root]
			while q:
				node = q.pop(0)
				if node.left:
					d[node.left.data] = node.data
					q.append(node.left)
				if node.right:
					d[node.right.data] = node.data
					q.append(node.right)
		d = {}
		d[root.data] = -1
		bfs(root, d)
		ans = []
		while target != -1:
			target = d[target]
			ans.append(target)
		return ans[:-1]


class Solution:

	def Ancestors(self, root, target):

		def dfs(root, key, arr):
			if not root:
				return False
			if root.data == key:
				return True
			if dfs(root.left, key, arr) or dfs(root.right, key, arr):
				arr.append(root.data)
			return arr
		return dfs(root, target, [])


class Solution:

	def Ancestors(self, root, target):
		ancs = []

		def rec(root):
			if not root:
				return False
			if root.data == target:
				return True
			if rec(root.left) or rec(root.right):
				ancs.append(root.data)
				return True
			return False
		rec(root)
		return ancs


class Solution:

	def helper_Ancestors(self, root, target, path):
		if root is None:
			return False
		if root.data == target:
			return True
		lt = self.helper_Ancestors(root.left, target, path)
		rt = self.helper_Ancestors(root.right, target, path)
		if lt or rt:
			path.append(root.data)
			return True
		else:
			return False

	def Ancestors(self, root, target):
		path = []
		ans = self.helper_Ancestors(root, target, path)
		return path


class Solution:

	def Ancestors(self, root, target):
		(x, f) = ([], 0)

		def ino(r, k):
			nonlocal f
			if not r:
				return
			if r.data == k:
				f = 1
				return
			if f == 0:
				x.append(r.data)
			ino(r.left, k)
			ino(r.right, k)
			if f != 1:
				x.pop()
		ino(root, target)
		return x[::-1]


class Solution:

	def Ancestors(self, root, target):
		ans = []

		def solve(root, target):
			if root is None:
				return None
			if root.data == target:
				return True
			left = solve(root.left, target)
			if left:
				ans.append(root.data)
				return True
			right = solve(root.right, target)
			if right:
				ans.append(root.data)
				return True
		solve(root, target)
		return ans


class Solution:

	def Ancestors(self, root, target):

		def solve(root, target):
			if root is None:
				return None
			if root.data == target:
				return True
			left = solve(root.left, target)
			if left != None:
				print(root.data, end=' ')
				return True
			right = solve(root.right, target)
			if right != None:
				print(root.data, end=' ')
				return True
		solve(root, target)
		return []


class Solution:

	def Ancestors(self, root, target):
		l = []
		path = []
		self.preorder(root, l, path)
		l = l[0]
		l.reverse()
		return l[1:]

	def preorder(self, root, l, path):
		if root:
			path.append(root.data)
			if root.data == target:
				l.append(path.copy())
			self.preorder(root.left, l, path)
			self.preorder(root.right, l, path)
			path.pop()


class Solution:

	def Ancestors(self, root, target):
		arr = []

		def func(root, tgt):
			if not root:
				return False
			if root.data == tgt:
				return True
			if func(root.left, tgt) or func(root.right, tgt):
				arr.append(root.data)
				return True
			return False
		func(root, target)
		return arr