題目
Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.
思路
分別求出跟節(jié)點(diǎn)到p,q的路徑龙亲，那么路徑的共同前綴的末尾即為所求。
代碼
# 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 visit(self, root, cur_path, pathes, p, q):
if root == None:
return
cur_path.append(root)
if root==p:
pathes.append(cur_path[:])
if root==q:
pathes.append(cur_path[:])
self.visit(root.left, cur_path, pathes, p, q)
self.visit(root.right, cur_path, pathes, p, q)
cur_path.pop()
def lowestCommonAncestor(self, root, p, q):
"""
:type root: TreeNode
:type p: TreeNode
:type q: TreeNode
:rtype: TreeNode
"""
if root == None:
return None
pathes = []
self.visit(root, [], pathes, p, q)
i = 0
while i < min(len(pathes[0]),len(pathes[1])):
if pathes[0][i] != pathes[1][i]:
break
i += 1
return pathes[0][i-1]
