LC-0404 Easy LeetCode

404. Sum of Left Leaves

Tree Depth-First Search Breadth-First Search Binary Tree

Read the full problem statement on LeetCode.

Difficulty: easy Acceptance: 62% Topics: Tree, Depth-First Search, Breadth-First Search, Binary Tree

Reading material

Reference solution (spoiler · python)

# Time:  O(n)
# Space: O(h)

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)

Solution from kamyu104/LeetCode-Solutions · MIT