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给定一个二叉树, 找到该树中两个指定节点的最近公共祖先。
百度百科中最近公共祖先的定义为:“对于有根树 T 的两个节点 p、q,最近公共祖先表示为一个节点 x,满足 x 是 p、q 的祖先且 x 的深度尽可能大(一个节点也可以是它自己的祖先)。”
# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def lowestCommonAncestor(self, root, p, q):
"""
:type root: TreeNode
:type p: TreeNode
:type q: TreeNode
:rtype: TreeNode
"""
self.ancest = None
self.p = p.val
self.q = q.val
def dfs(root):
if root ==None:
return False , False
left_p, left_q = dfs(root.left)
right_p , right_q = dfs(root.right)
get_p = left_p or right_p
get_q = left_q or right_q
# print(get_p)
if self.p == root.val:
get_p = True
if self.q == root.val:
get_q = True
if self.ancest == None and get_p and get_q:
self.ancest = root
return get_p, get_q
dfs(root)
return self.ancest