[LeetCode] Sum of Left Leaves 파이썬 (Tree)

class Solution(object):
    def sumOfLeftLeaves(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        def sumOfLeftLeavesHelper(root, is_left):
            if not root:
                return 0
            if not root.left and not root.right:
                return root.val if is_left else 0
            return sumOfLeftLeavesHelper(root.left, True) + sumOfLeftLeavesHelper(root.right, False)

        return sumOfLeftLeavesHelper(root, False)

leaf 노드 까지 탐색한다.

left일 경우에만 +

 

출처: github.com/jiapengwen/LeetCode/blob/master/Python/sum-of-left-leaves.py