HEADSHOT - Headshot

no tags 

You have a revolver gun with a cylinder that has n chambers. Chambers are located in a circle on a cylinder. Each chamber can be empty or can contain a round. One chamber is aligned with the gun's barrel. When trigger of the gun is pulled, the gun's cylinder rotates, aligning the next chamber with the barrel, hammer strikes the round, making a shot by firing a bullet through the barrel. If the chamber is empty when the hammer strikes it, then there is no shot but just a "click".

You have found a use for this gun. You are playing Russian Roulette with your friend. Your friend loads rounds into some chambers, randomly rotates the cylinder, aligning a random chamber with a gun's barrel, puts the gun to his head and pulls the trigger. You hear "click" and nothing else - the chamber was empty and the gun did not shoot.

Now it is your turn to put the gun to your head and pull the trigger. You have a choice. You can either pull the trigger right away or you can randomly rotate the gun's cylinder and then pull the trigger. What should you choose to maximize the chances of your survival?


The input first line contains a single line with a string of n digits "0" and "1" (2 <= n <= 100). This line of digits represents the pattern of rounds that were loaded into the gun's chambers. "0" represent an empty chamber, "1" represent a loaded one. In this representation, when cylinder rotates before a shot, the next chamber to the right gets aligned with the barrel for a shot. Since the chambers are actually located on a circle, the first chamber in this string follows the last one. There is at least one "0" in this string.


Write to the output single one of the following words (without quotes):

  • "SHOOT" - if pulling the trigger right away makes you less likely to be actually shot in the head with the bullet (more likely that the chamber will be empty).
  • "ROTATE" - if randomly rotating the cylinder before pulling the trigger makes you less likely to be actually shot in the head with the bullet (more likely that the chamber will be empty).
  • "EQUAL" - if both of the above choices are equal in terms of probability of being shot.





hide comments
anonymousamigo: 2018-08-08 12:48:41

It is a simple counting Problem.

studyfather: 2017-07-26 13:58:33

a great math problem!

sayantan96: 2016-07-02 15:42:33

This is a great question!

Shivam Singh: 2015-08-19 16:13:31

EQUAL also implies the situation when the possibility of being saved is same whether you rotate or shoot,
thus 000 or 0000 would be EQUAL.
To implement the circular array just do A[(i-1+N)%N] instead of A[i-1] if you are getting stuck

[Mayank Pratap]: 2015-07-21 06:47:08

AC in one go....Nice Problem ... :) :)

Dushyant Singh: 2015-07-19 17:44:04

Can someone explain why is the answer for 000 EQUAL?

i_am_looser: 2015-05-25 15:24:07

Something is wrong with this question... i found two code for this problem from net.... for string 001 one gave EQUAL and other ROTATE but both got accepted..... can anyone tell me why this happened.....

vaibhav jain: 2015-05-24 14:35:23

got it

Last edit: 2015-05-24 14:43:24
SHIVAM DIXIT: 2014-09-29 17:24:41

please explain these test cases...

Anubhav Balodhi : 2014-07-06 19:56:45

taking headshot was never this much fun, gud question :-)
sopved using probability ^_^

Added by:Gareev
Time limit:0.208s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: NODEJS OBJC PERL6 VB.NET
Resource:NEERC 2009