Java | Leetcode Java题解之第404题左叶子之和
题目：
题解：
class Solution {
public int sumOfLeftLeaves(TreeNode root) {
if (root == null) {
return 0;
}
Queue<TreeNode> queue = new LinkedList<TreeNode>();
queue.offer(root);
int ans = 0;
while (!queue.isEmpty()) {
TreeNode node = queue.poll();
if (node.left != null) {
if (isLeafNode(node.left)) {
ans += node.left.val;
} else {
queue.offer(node.left);
}
}
if (node.right != null) {
if (!isLeafNode(node.right)) {
queue.offer(node.right);
}
}
}
return ans;
}
public boolean isLeafNode(TreeNode node) {
return node.left == null && node.right == null;
}
}