LeetCode: Sum of Left Leaves

LeetCode: Sum of Left Leaves

Find the sum of all left leaves in a given binary tree.

Example:

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2
3
4
5
6
7
    3
/ \
9 20
/ \
15 7

There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.
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33
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public int sumOfLeftLeaves(TreeNode root) {
if (root == null) {
return 0;
}
int result = 0;
Queue<TreeNode> queue = new LinkedList<>();
queue.add(root);
while (!queue.isEmpty()) {
TreeNode node = queue.poll();
if (node.left != null && node.left.left == null && node.left.right == null) {
result += node.left.val;
}

if (node.left != null) {
queue.add(node.left);
}
if (node.right != null) {
queue.add(node.right);
}
}
return result;
}
}