问题描述
问题分析
代码实现
public int sumOfLeftLeaves(TreeNode root) {
if (root == null) {
return 0;
}
int res = 0;
if (root.left != null) {
res += (root.left.left == null && root.left.right == null) ? root.left.val : sumOfLeftLeaves(root.left);
}
res += sumOfLeftLeaves(root.right);
return res;
}
public int sumOfLeftLeaves(TreeNode root) {
if (root == null) {
return 0;
}
int sum = 0;
LinkedList<TreeNode> queue = new LinkedList<>();
queue.add(root);
while (! queue.isEmpty()) {
TreeNode node = queue.remove();
if (node.left != null) {
if (node.left.left == null && node.left.right == null) {
sum += node.left.val;
}else {
queue.add(node.left);
}
}
if (node.right != null) {
queue.add(node.right);
}
}
return sum;
}