标签：hat 左右子树 等于 同步 none example upload 相同 Plan
题目如下：
For a binary tree T, we can define a flip operation as follows: choose any node, and swap the left and right child subtrees.
A binary tree X is flip equivalent to a binary tree Y if and only if we can make X equal to Y after some number of flip operations.
Write a function that determines whether two binary trees are flip equivalent. The trees are given by root nodes
root1androot2.
Example 1:
Input: root1 = [1,2,3,4,5,6,null,null,null,7,8], root2 = [1,3,2,null,6,4,5,null,null,null,null,8,7] Output: true Explanation: We flipped at nodes with values 1, 3, and 5.
Note:
- Each tree will have at most
100nodes.- Each value in each tree will be a unique integer in the range
[0, 99].
解题思路：从两个根节点开始分别同步遍历两棵树，如果左右子树相同则表示不用交换；如果左右互相等于对方则交换；否则表示无法交换。
代码如下：
# 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): res = True def verify(self,node1,node2): leftV1 = None if node1.left == None else node1.left.val leftV2 = None if node2.left == None else node2.left.val rightV1 = None if node1.right == None else node1.right.val rightV2 = None if node2.right == None else node2.right.val if leftV1 == leftV2 and rightV1 == rightV2: return 0 elif leftV1 == rightV2 and rightV1 == leftV2: return 1 else: return -1 def traverse(self,node1,node2): if node1 == None or node2 == None: return ret = self.verify(node1,node2) if ret == 0: self.traverse(node1.left,node2.left) self.traverse(node1.right, node2.right) elif ret == 1: node2.left,node2.right = node2.right,node2.left self.traverse(node1.left, node2.left) self.traverse(node1.right, node2.right) else: self.res = False def flipEquiv(self, root1, root2): """ :type root1: TreeNode :type root2: TreeNode :rtype: bool """ if (root1 == None) ^ (root2 == None): return False self.res = True self.traverse(root1,root2) return self.res
【leetcode】951. Flip Equivalent Binary Trees
标签：hat 左右子树 等于 同步 none example upload 相同 Plan
原文地址：https://www.cnblogs.com/seyjs/p/10084253.html
