Just do a level order traversal and calcualte the sum. When your queue is empty, the last sum will be your answer, i.e. the sum of the lowest level\n\n\'\'\'\n\t\n\tpublic int deepestLeavesSum(TreeNode root) {\n        \n        Queue<TreeNode> q = new LinkedList<>();\n\t\tq.offer(root);\n\t\tint sum = 0;\n\t\twhile(!q.isEmpty())\n\t\t{\n\t\t\tint ql = q.size();\n\t\t\tsum = 0;\n\t\t\twhile(ql-- > 0)\n\t\t\t{\n\t\t\t\tTreeNode curr = q.poll();\n\t\t\t\tsum += curr.val;\n\t\t\t\tif(curr.left!=null)\n\t\t\t\t\tq.offer(curr.left);\n\t\t\t\tif(curr.right!=null)\n\t\t\t\t\tq.offer(curr.right);\n\t\t\t}\n\t\t}\n\t\t\n\t\treturn sum;\n\'\'\'

Just do a level order traversal and calcualte the sum. When your queue is empty, the last sum will be your answer, i.e. the sum of the lowest level\n\n\'\'\'\n\