DIVISION - Divisiblity by 3

Divisiblity by 3 rule is pretty simple rule: Given a number sum the digits of number and check if sum is divisible by 3.If divisible then it is divisible by 3 else not divisible.Seems pretty simple but what if we want to extend this rule in binary representation!!

Given a binary representation we can again find if it is divisible by 3 or not. Making it little bit interesting what if only length of binary representation of a number is given say n.

Now can we find how many numbers exist in decimal form (base 10) such that when converted into binary (base 2) form has n length and is divisible by 3 ?? (1 <= n < 2*10^18)


Length of binary form: n


Print in new line the answer modulo 1000000007.






Explanation: For n=2 there are only 2 numbers divisible by 3 viz.0 (00) and 3 (11) and having length 2 in binary form.

NOTE: There are multiple testfiles containing many testcases each so read till EOF.

Warnings: Leading zeros are allowed in binary representation and slower languages might require fast i/o. Take care.

hide comments
Rahul Jain: 2014-09-27 15:01:34

Please tell me why my code is giving WA,
link is here-->**removed**
and @admin, submission id is 12455336

--bhavik--> kindly do not post link to your code!! and your logic is wrong

Last edit: 2014-09-30 17:38:47
albertg: 2014-09-25 18:18:31

I'm using scanf/printf, my algorithm is O(logn), but I get TLE :(

Rahul Jain: 2014-09-25 10:56:34

Last edit: 2014-09-28 10:01:49
Amitayush Thakur: 2014-08-28 14:23:25

Time limit very strict.

Wonderwice Margera: 2014-08-26 12:48:21

Could admin please take a look at submission id 12237897 and give some idea of what it is doing wrong? The code seemed to work properly in the cases I tried out.

--bhavik--> Have you tried large testcases like 10^10 or above..!!Test for large cases you will find your mistake,good luck:)

--Thanks for the hint, it worked out :)

Last edit: 2014-08-28 18:10:37
johri: 2014-07-30 22:07:41

any range for n bhavik .!

--bhavik--> read question again for your answer,good luck.

Last edit: 2014-07-31 10:49:47
રચિત (Rachit): 2014-07-14 09:41:19

isn't the time limit too strict for languages like python?

785227: 2014-07-02 18:21:34

Very good problem indeed :)

.:frUstrAteD:.: 2014-07-01 18:55:46

gud ques. need many optimizations
use scanf,printf for i/o
cin,cout gives TLE

Last edit: 2014-07-01 19:03:46
pika_pika: 2014-06-30 19:02:39

strict time limit. Java using BufferedReader times out at test case #5.

Last edit: 2014-06-30 19:04:27

Added by:Bhavik
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ASM64