.::Kotlin::. BFS, Right -> Left
In BFS, add right node before the left. So at last level, last element is left most element.\n\n\nclass Solution {\n    fun findBottomLeftValue(root: TreeNode?)
In BFS, add right node before the left. So at last level, last element is left most element.\n\n```\nclass Solution {\n    fun findBottomLeftValue(root: TreeNode?): Int {\n        if (root == null) return -1\n        \n        val q = LinkedList<TreeNode>()\n        q += root\n\n        var res: TreeNode = root\n        while (q.isNotEmpty()) {\n            res = q.poll()\n            res.right?.let { q += it }\n            res.left?.let { q += it }\n        }\n\n        return res.`val`\n    }\n}\n```
['Kotlin']