0965. Univalued Binary Tree

https://leetcode.com/problems/univalued-binary-tree

Description

A binary tree is uni-valued if every node in the tree has the same value.

Given the root of a binary tree, return true if the given tree is uni-valued, or false otherwise.

Example 1:

**Input:** root = [1,1,1,1,1,null,1]
**Output:** true

Example 2:

**Input:** root = [2,2,2,5,2]
**Output:** false

Constraints:

• The number of nodes in the tree is in the range [1, 100].

• 0 <= Node.val < 100

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