# 1022. Sum of Root To Leaf Binary Numbers

https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers

## Description

You are given the `root` of a binary tree where each node has a value `0` or `1`.  Each root-to-leaf path represents a binary number starting with the most significant bit.  For example, if the path is `0 -> 1 -> 1 -> 0 -> 1`, then this could represent `01101` in binary, which is `13`.

For all leaves in the tree, consider the numbers represented by the path from the root to that leaf.

Return _the sum of these numbers_. The answer is **guaranteed** to fit in a **32-bits** integer.

**Example 1:**

![](https://assets.leetcode.com/uploads/2019/04/04/sum-of-root-to-leaf-binary-numbers.png)

```
**Input:** root = [1,0,1,0,1,0,1]
**Output:** 22
**Explanation:** (100) + (101) + (110) + (111) = 4 + 5 + 6 + 7 = 22
```

**Example 2:**

```
**Input:** root = [0]
**Output:** 0
```

**Example 3:**

```
**Input:** root = [1]
**Output:** 1
```

**Example 4:**

```
**Input:** root = [1,1]
**Output:** 3
```

**Constraints:**

* The number of nodes in the tree is in the range `[1, 1000]`.
* `Node.val` is `0` or `1`.

## ac

```java
```
