BEENUMS - Beehive Numbers

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A beehive is an enclosed structure in which some honey bee species live and raise their
young. In this problem we consider a two-dimensional sketch of the beehives. Each
beehive is composed of a certain number of cells, where each cell is a regular hexagon.
Each cell may have some neighbors, which are other cells that share a side with that cell.
A cell with exactly 6 neighbors is an internal cell, while a cell with fewer neighbors is an
external one. Notice that an external cell can always be changed to internal by adding
some neighbor cells.

We are interested in a particular class of beehives. This class of valid beehives is defined
recursively as follows: a) a single cell is a valid beehive; and b) given a valid beehive B,
if we add the minimum number of cells such that each external cell of B becomes an
internal cell, the result is a valid beehive.

The number of cells in a valid beehive is called a beehive number. Given an integer N ,
you must decide whether it is a beehive number.


Each test case is described using a single line. The line contains an integer N (1 ≤ N ≤
109 ). The end of input is indicated with a line containing a single −1.


For each test case, output a single line containing an uppercase “Y” if N is a beehive
number, or an uppercase “N” otherwise.



hide comments
spartax: 2016-12-06 22:30:34

See the sequence 1, 1 + 6, 1 + 6 + 12, ... and you will get the solution

Simran Saha: 2016-11-18 08:03:47

I am having difficulty in understanding the problem. Can anybody give a better explanation?

epsilonalpha: 2016-11-03 02:38:34

48th :)
Very simple, AC in one go, 0 sec.

narutohokage_1: 2016-10-23 08:55:29

Do not see comments for hint . Because you can always find a better method , find your own method (Some methods in comment are more time efficient than others so you must try it yourself and then optimize it if it fails) , question is easy . Do not give up and draw diagram for more understanding. Also dont forget it Y and N not Yes and No.

angel_of_death: 2016-10-21 19:32:12

Was printing something out to debug the code and forgot to comment it out before submitting. Resulted in multiple WA. FML!

sayedathar11: 2016-08-18 15:27:59

Very Easy problem if You can observe pattern and apply brute force :) ;)

ghost_wire: 2016-07-29 08:38:53

comment helps a lot but it also destroy the pleasure of problem so please don't post the logic only post hint to that.

sssymm: 2016-07-27 05:08:42

@vector1996 touche

vector1996: 2016-07-15 20:01:43

long - WA
long long - AC

SANDEEP KUMAR: 2016-07-12 11:38:56

Solved each query in O(1) with a bit precomputation...

Added by:Pablo Ariel Heiber
Time limit:0.666s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: NODEJS objc
Resource:FCEyN UBA ICPC Selection 2010