Simple solution by using the Concept of BFS Traversal
Intuition: \nThe code needs to return the bottem left value of the tree to find the bottom left we need to traverse the tree level by level this can be done by 
# Intuition: \nThe code needs to return the bottem left value of the tree to find the bottom left we need to traverse the tree level by level this can be done by BFS Traversal using Queue Data Structure\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach:\n1)we take an empty queue and add the root value to it.\n2)pop the first element in the queue and check wheather there exists left or right \n3)if exists add them into the queue \nnote:while poping store the poped element in any variable (ex :k=queue.pop(0))by using k find the existence if next left and right values\n4)if k.left!=None then add k.left  into the Queue\n5)if l.right!=None then add k.right into the Queue \n6)do this from step 2 to 5 until the queue becomes empty\n7)after the queue becomes empty the k contains the bottom left tree value \n   Finally return k.Val\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:O(n)\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:O(m) where m is themaximum no of nodes at any level in a binary tree\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\n# Definition for a binary tree node.\n# class TreeNode:\n#     def __init__(self, val=0, left=None, right=None):\n#         self.val = val\n#         self.left = left\n#         self.right = right\nclass Solution:\n    def findBottomLeftValue(self, root: Optional[TreeNode]) -> int:\n        queue=[]\n        return bfs(root,queue)\n\ndef bfs(root,queue):\n    if root!=None:\n        queue.append(root)\n    while(len(queue)):\n        k=queue.pop(0)\n        print(k.val,end=" ")\n        if k.right!=None:\n            queue.append(k.right)\n        if k.left!=None:\n            queue.append(k.left)\n        \n    return k.val\n\n        \n```
['Python', 'Python3']