我使用递归为leetcode问题编写了代码“108. Left of Left Leaves”。它没有给我预期的结果。
# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def sumOfLeftLeaves(self, root):
"""
:type root: TreeNode
:rtype: int
"""
if root is None:
return 0
ans = 0
if root.left and not root.left.left and not root.left.right:
ans += root.left.val
self.sumOfLeftLeaves(root.left)
self.sumOfLeftLeaves(root.right)
return ans
输入为[3,9,20时,null,null,15,7]
我预计会返回24,但代码只给了我9
您没有在根目录下添加叶子的结果。你需要这个:
class Solution(object):
def sumOfLeftLeaves(self, root):
"""
:type root: TreeNode
:rtype: int
"""
if root is None:
return 0
ans = 0
if root.left and not root.left.left and not root.left.right:
ans += root.left.val
ans += self.sumOfLeftLeaves(root.left) + self.sumOfLeftLeaves(root.right)
return ans