513\. Find Bottom Left Tree Value

Medium

Given the `root` of a binary tree, return the leftmost value in the last row of the tree.

**Example 1:**

![](https://assets.leetcode.com/uploads/2020/12/14/tree1.jpg)

**Input:** root = [2,1,3]

**Output:** 1

**Example 2:**

![](https://assets.leetcode.com/uploads/2020/12/14/tree2.jpg)

**Input:** root = [1,2,3,4,null,5,6,null,null,7]

**Output:** 7

**Constraints:**

*   The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.
*   <code>-2<sup>31</sup> <= Node.val <= 2<sup>31</sup> - 1</code>