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1302. Deepest Leaves Sum

Difficulty Topics

Description

Given the root of 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

Example 2:

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

 

Constraints:

  • The number of nodes in the tree is in the range [1, 104].
  • 1 <= Node.val <= 100

Solution

deepest-leaves-sum.py
# 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 deepestLeavesSum(self, root: TreeNode) -> int:

        def depth(node):
            if not node: return 0

            return 1 + max(depth(node.left), depth(node.right))

        d = depth(root)
        res = 0
        q = collections.deque([(root, 1)])

        while q:
            node, depth = q.popleft()

            if depth == d: res += node.val

            for leaf in (node.left, node.right):
                if leaf:
                    q.append((leaf, depth + 1))

        return res