LeetCode: Find Bottom Left Tree Value

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int findBottomLeftValue(TreeNode root) {
        Deque<TreeNode> row = new LinkedList<TreeNode>();
        row.add(root);
        int ans = 0;
        while (row.isEmpty() != true) {
            int size = row.size();
            for (int i = 0; i < size; i++) {
                TreeNode node = row.poll();
                if (i == 0) ans = node.val;
                if (node.left != null) row.add(node.left);
                if (node.right != null) row.add(node.right);
            }
        }
        return ans;
    }
}