Python describe LeetCode 513. Find the value in the lower left corner of the tree

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subject

Given a binary tree The root node root, Please find the of the binary tree At the bottom Leftmost The value of the node .

Suppose there is at least one node in the binary tree .

Example 1:

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

Example 2:

 Input : [1,2,3,4,null,5,6,null,null,7]
Output : 7

Tips :

• The range of the number of nodes in a binary tree is [1,104]
• -231 <= Node.val <= 231 - 1

Python describe

Traverse the hierarchy , Find the first node at the lowest level

# 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:
q = [root]
res = None
while q != []:
res = q[0].val
for _ in range(len(q)):
if q[0].left:
q.append(q[0].left)
if q[0].right:
q.append(q[0].right)
q.remove(q[0])
return res