<p>Given the <code>root</code> of a binary tree, return the leftmost value in the last row of the tree.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/12/14/tree1.jpg" style="width: 302px; height: 182px;" />
<pre>
<strong>Input:</strong> root = [2,1,3]
<strong>Output:</strong> 1
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/12/14/tree2.jpg" style="width: 432px; height: 421px;" />
<pre>
<strong>Input:</strong> root = [1,2,3,4,null,5,6,null,null,7]
<strong>Output:</strong> 7
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

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

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def findBottomLeftValue(self, root: Optional[TreeNode]) -> int:
        self.bfs_arr=[]
        self.q = deque()
        self.q.append(root)
        self.helper()
        print(self.bfs_arr)
        return self.bfs_arr[-1][0]

    def helper(self):
     
        while self.q:
            level =[]
            n = len(self.q)
            for i in range(n):
                node = self.q.popleft()
                level.append(node.val)
                if node.left:
                    self.q.append(node.left)
                if node.right:
                     self.q.append(node.right)   
            self.bfs_arr.append(level)


    #     self.levelLeft = -1
    #     self.levelRight = -1

    #     return self.helper(root)

    # def helper(self, node):
    #     if not node:
    #         return 
    #     if not node.left and not node.right:
    #         return  node.val# this indicates it's a leaf node

    #     if node.left:
    #         left_val = self.helper(node.left)
    #         self.levelLeft += 1
    #     if node.right:
    #         right_val = self.helper(node.right)
    #         self.levelRight += 1
    #     if left_val and self.levelLeft >= self.levelRight:
    #         self.levelLeft = -1
    #         return left_val 
            
    #     else:
    #         self.levelRight = -1
    #         return right_val


18800