计算给定二叉树的所有左叶子之和。
示例:
3
/ \
9 20
/ \
15 7
在这个二叉树中,有两个左叶子,分别是 9 和 15,所以返回 24
方法一:
# 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 sumOfLeftLeaves(self, root: TreeNode) -> int:
if root == None:
return 0
if root.left and root.left.left == None and root.left.right == None:
return root.left.val + self.sumOfLeftLeaves(root.right)
else:
return self.sumOfLeftLeaves(root.left) + self.sumOfLeftLeaves(root.right)
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