leetcode199_二叉树的右视图
public List<Integer> rightSideView(TreeNode root) {
List<Integer> list = new ArrayList();
if(root == null) return list;
Deque<TreeNode> q = new LinkedList();
q.offer(root);
while(!q.isEmpty()) {
int size = q.size();
for(int i = 0; i < size; i++) {
TreeNode node = q.poll();
if(node.left != null) q.offer(node.left);
if(node.right != null) q.offer(node.right);
if(i == size-1) list.add(node.val);
}
}
return list;
}