leetcode1302 Deepest Leaves Sum

"""
Given a binary tree, return the sum of values of its deepest leaves.
Example 1:
Input: root = [1,2,3,4,5,null,6,7,null,null,null,null,8]
Output: 15
"""
"""
层次遍历
"""
class TreeNode:
    def __init__(self, x):
        self.val = x
        self.left = None
        self.right = None

class Solution:
    def deepestLeavesSum(self, root):
        if root == None:
            return 0
        queue = []
        queue.append(root)
        while queue:
            res = 0
            newqueue = []
            n = len(queue)
            for _ in range(n):
                x = queue.pop(0)
                res += x.val
                if x.left != None:
                    newqueue.append(x.left)
                if x.right != None:
                    newqueue.append(x.right)
            queue = newqueue
        return res