Map<Integer,Integer> map = new HashMap<>();
public int findBottomLeftValue(TreeNode root) {
if (root == null) return 0;
LinkedList<TreeNode> deque = new LinkedList<>();
while(!deque.isEmpty()) {
for (int i = 0; i < size; i++) {
TreeNode node = deque.pollFirst();
if (node.left != null)deque.addLast(node.left);
if (node.right != null)deque.addLast(node.right);