【leetcode】965. Univalued Binary Tree

发布时间：2020-12-14 05:17:39 所属栏目：大数据来源：网络整理

导读：题目如下： A binary tree is? univalued ?if every node in the tree has the same value. Return? true ?if and only if the given tree is univalued. ? Example 1: Input: [1,1,null,1]Output: true Example 2: Input: [2,2,5,2]Output: false ? Note: T

题目如下：

A binary tree is?univalued?if every node in the tree has the same value.

Return?true?if and only if the given tree is univalued.

?

Example 1:
Input: [1,1,null,1]
Output: true 
Example 2:
Input: [2,2,5,2]
Output: false 
?

Note:

The number of nodes in the given tree will be in the range?[1,100].

Each node‘s value will be an integer in the range?[0,99].

解题思路：送分题。

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):
    def recursive(self,node,v):
        if node.val != v:
            return False
        r1 = r2 = True
        if node.left != None:
            r1 = self.recursive(node.left,v)
        if node.right != None:
            r2 = self.recursive(node.right,v)
        return r1 and r2

    def isUnivalTree(self,root):
        """
        :type root: TreeNode
        :rtype: bool
        """
        if root == None:
            return True
        return self.recursive(root,root.val)

（编辑：李大同）

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