# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def isUnivalTree(self, root: TreeNode) -> bool:
        # left_correct = (not root.left or root.val == root.left.val
        #         and self.isUnivalTree(root.left))
        # right_correct = (not root.right or root.val == root.right.val
        #         and self.isUnivalTree(root.right))
        # return left_correct and right_correct
        vals = []

        def dfs(node):
            if node:
                vals.append(node.val)
                dfs(node.left)
                dfs(node.right)

        dfs(root)
        return len(set(vals)) == 1

"""
965. Univalued Binary Tree
Easy

363

39

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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: [1,1,1,1,1,null,1]
Output: true
Example 2:


Input: [2,2,2,5,2]
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].

"""