# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
if not root:
return root
if root.val == p.val or root.val == q.val:
return root
l = self.lowestCommonAncestor(root.left, p, q)
r = self.lowestCommonAncestor(root.right, p, q)
if l and r:
return root
if l:
return l
if r:
return r
首先确定使用递归的思想先写出
l = self.lowestCommonAncestor(root.left, p, q)
r = self.lowestCommonAncestor(root.right, p, q)
然后在考虑返回值如果pq在root的左右两边，那么最近公共祖先肯定是root
如果都在左边，那么公共祖先就是l
如果都在右边，那么公共祖先就是r
if l and r:
return root
if l:
return l
if r:
return r
最后确定迭代的终止条件
