Breadth First Search $$(BFS)$$ is started on a binary tree beginning from the root vertex. There is a vertex $$t$$ at a distance four from the root. If t is the $$n$$-th vertex in this $$BFS$$ traversal, then the maximum possible value of $$n$$ is ___________.

Consider the following $$New-order$$ strategy for traversing a binary tree:

$$\,\,\,\,\,\,\, \bullet \,\,\,\,\,$$ Visit the root;
$$\,\,\,\,\,\,\, \bullet \,\,\,\,\,$$ Visit the right subtree using $$New-order;$$
$$\,\,\,\,\,\,\, \bullet \,\,\,\,\,$$ Visit the left subtree using $$New-order;$$

The New-order traversal of the expression tree corresponding to the reverse polish expression 3 4 * 5 - 2 ^ 6 7 * 1 + - is given by:

In an adjacency list representation of an undirected simple graph $$G = (V,E),$$ each edge $$(u, v)$$ has two adjacency list entries: $$[v]$$ in the adjacency list of $$u,$$ and $$[u]$$ in the adjacency list of $$v.$$ These are called twins of each other. A twin pointer is a pointer from an adjacency list entry to its twin. If $$|E| = m$$ and $$|V| = n,$$ and the memory size is not a constraint, what is the time complexity of the most efficient algorithm to set the twin pointer in each entry in each adjacency list?

The number of ways in which the numbers $$1, 2, 3, 4, 5, 6, 7$$ can be inserted in an empty binary search tree, such that the resulting tree has height $$6,$$ is _____________.

$$Note:\,\,\,The\,\,height\,\,of\,\,a\,tree\,\,with\,\,a\,\,\sin gle\,\,node\,\,is\,\,0$$