Sum of Left Leaves
Given the root of a binary tree, return the sum of all left leaves.
A leaf is a node with no children. A left leaf is a leaf that is the left child of another node.
Example 1
3
/ \
9 20
/ \
15 7Input
root = [3,9,20,null,null,15,7]Output
24There are two left leaves in the binary tree, with values 9 and 15 respectively.
Example 2
1
Input
root = [1]Output
0The only node is the root, so there are no left leaves.
Constraints
- The number of nodes in the tree is in the range
[1, 1000]. -1000 <= Node.val <= 1000