题目：

题解：

class Solution {public int findBottomLeftValue(TreeNode root) {int ret = 0;Queue<TreeNode> queue = new ArrayDeque<TreeNode>();queue.offer(root);while (!queue.isEmpty()) {TreeNode p = queue.poll();if (p.right != null) {queue.offer(p.right);}if (p.left != null) {queue.offer(p.left);}ret = p.val;}return ret;}
}