## Castle Invasion

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Points: 10 (partial)
Time limit: 2.0s
PyPy 2 5.0s
PyPy 3 5.0s
Memory limit: 64M
PyPy 2 256M
PyPy 3 256M

Authors:
Problem type

Bob is planning an attack on a suspicious castle owned by the evil villain Joe! The castle can be thought of as an by grid of towers, with each tower having an integer height. To scout for this attack, Bob sent his only drone that can instantly transmit pictures to take photos of the castle. However, the drone only managed to take 2 photos before critically running out of battery and tumbling into the forest. One photo was taken of the front side of the castle, while the other captured its right side. It was also discovered (slightly too late) that the drone's camera cannot capture depth! Since Bob does not want to fail this attack, he would like to know the maximum possible volume of the castle, or if the photos are incorrect and a castle cannot be reconstructed. Can you help him find out?

#### Input Specification

The first line of the input will contain an integer , representing the dimensions of the castle.

The second line will contain integers , representing the height of the tallest tower in the th column.

The third line will contain integers , representing the height of the tallest tower in the th row.

#### Output Specification

A single integer, representing the maximum possible volume of the castle, or -1 if it is impossible to reconstruct a castle.

#### Sample Input 1

4
1 3 4 2
2 2 1 4

#### Sample Output 1

28

#### Sample Input 2

4
1 2 6 2
5 3 3 3

#### Sample Output 2

-1

#### Explanation for Sample Output 2

No matter how you assign heights to each tower, it is impossible to reconstruct a castle that satisfies both photos.

• pblpbl  commented on Oct. 19, 2019, 9:56 a.m.

I finally got this after 3 days! This is a good problem.

• 4fecta  commented on Oct. 19, 2019, 2:25 p.m.

• d  commented on Oct. 16, 2019, 3:22 p.m.

no, it is not necessary to create an n by n grid

• pblpbl  commented on Oct. 17, 2019, 5:34 p.m.

i'm still stuck on the second last case... hint pls?

• 4fecta  commented on Oct. 17, 2019, 11:31 p.m. edited

Your code has a time complexity of , which is too slow to pass the second subtask. Try thinking of how you can optimize your algorithm to a better complexity.

• pblpbl  commented on Oct. 16, 2019, 1:57 p.m. edited

Is an N by N grid required to solve this problem? I am getting a memory error at the second last test case.