# Univalue Tree Count

A univalue tree is a tree where all nodes under it have the same value.

Given a binary tree `root`

, return the number of univalue subtrees.

**Constraints**

`1 ≤ n ≤ 100,000`

where`n`

is the number of nodes in`root`

https://binarysearch.com/problems/Univalue-Tree-Count

## Examples

### Example 1

**Input**

- root =

**Output**

- answer =
`2`

**Explanation**

The two leaf nodes are unival trees.

### Example 2

**Input**

- root =

**Output**

- answer =
`5`

**Explanation**

The unival trees include four leaf nodes (three of them are `1`

s, the other one is the rightmost `0`

), and one subtree in the middle (containing all `1`

s).

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