# LeetCode 1302. Deepest Leaves Sum

###### tags: `python`,`LeetCode`
>這邊使用Python解題

## 題目：
Given the root of a binary tree, return the sum of values of its deepest leaves.

## 範例
### 範例 1:

Input: root = [1,2,3,4,5,null,6,7,null,null,null,null,8]
Output: 15

### 範例 2:

Input: root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5]
Output: 19

## 條件限制
* The number of nodes in the tree is in the range [1, 104].
* 1 <= Node.val <= 100

## 我的解題思路：
這一題蠻複雜的，需要我們去走訪一顆二元樹，那二元樹走訪主要有BFS與DFS，那我這邊為了要記錄走訪的深度所以使用BFS，資料結構選用queuq來實作，將每一層的節點val加總，並且回傳最深層的加總值

## 程式碼:

def deepestLeavesSum(self, root: Optional[TreeNode]) -> int:
    d = deque([root])
    result = [root.val]
    level = 0
    while(len(d)>0):
        level +=1
        a = []
        while(len(d)>0):
            cur = d.pop()
            a.extend([x for x in (cur.left, cur.right) if x != None])
        if len(a)>0:
            result.append(sum([x.val for x in a]))
                d.extend(a)
        return result[level-1]