The final exam is here, and it's now or never for Ethan. His current grade is abysmal so he needs a strong showing on this exam to have any chance of passing his introductory computer science class.
The exam has only one question: devise an algorithm to compute the compactness of a grid tree.
Ethan recalls that a "grid tree" is simply an unweighted tree with 2N nodes that you can imagine being embedded within a 2xN grid. The top row of the grid contains the nodes 1 ... N from left to right, and the bottom row of the grid contains the nodes (N + 1) ... 2N from left to right. Every edge in a grid tree connects a pair of nodes which are adjacent in the 2xN grid. Two nodes are considered adjacent if either they're in the same column, or they're directly side-by-side in the same row. There must be exactly 2N-1 edges that connect the 2N nodes to form a single tree. Additionally, the ith node in the grid tree is labelled with an integer Ai.
What was "compactness" again? After some intense thought, Ethan comes up with the following pseudocode to compute the compactness, c, of a grid tree:
ShortestDistance(i, j)
ShortestDistance(i, j)
is a function which returns the number of edges on the shortest path from node i to node j in the tree,
which Ethan has implemented correctly. In fact, his whole algorithm is quite correct for once. This is exactly how you compute compactness!
There's just one issue — in his code, Ethan has chosen to store c using a rather small integer type, which is at risk of overflowing if c becomes too large!
Ethan is so close! Feeling sorry for him, you'd like to make some last-minute changes to the tree in order to minimize the final value of c, and thus minimize the probability that it will overflow in Ethan's program and cost him much-needed marks. You can't change any of the node labels A1..2N, but you may choose your own set of 2N - 1 edges to connect them into a grid tree.
For example, if A = [1, 3, 2, 2, 4, 5], then the grid of nodes looks like this:
You'd like to determine the minimum possible compactness which Ethan's program can produce given a valid tree of your choice. For example, one optimal tree for the above grid of nodes (which results in the minimum possible compactness of 198) is as follows:
Input begins with an integer T, the number of trees. For each tree, there are three lines. The first line contains the single integer N. The second line contains the N space-separated integers A1..N. The third line contains the N space-separated integers AN+1..2N.
For the ith tree, output a line containing "Case #i: " followed by the minimum possible output of Ethan's program.
1 ≤ T ≤ 80
1 ≤ N ≤ 50
1 ≤ Ai ≤ 1,000,000
One optimal tree for the first case is given above. For that tree, Ethan's program would compute c as the sum of the following values (with some values omitted):
ShortestDistance(1, 2)
= 1 * 3 * 1 = 3
ShortestDistance(1, 3)
= 1 * 2 * 4 = 8
ShortestDistance(1, 6)
= 1 * 5 * 3 = 15
ShortestDistance(2, 3)
= 3 * 2 * 3 = 18
ShortestDistance(4, 6)
= 2 * 5 * 2 = 20
ShortestDistance(5, 6)
= 4 * 5 * 1 = 20
In the second case, there's only one possible tree, for which c = 2 * 3 * 1 = 6.
In the third case, two of the four possible trees are optimal (the ones omitting either the topmost or leftmost potential edge).