CHANDF - EDITORIAL

harshil21 · May 13, 2020, 6:49am

Try L = R = 0 in your code and try even try generating some random cases as well.

abhaypatil2000 · May 13, 2020, 7:16am

because 2 ^42 is > 10^12, which is the upper limit

anon68898643 · May 13, 2020, 8:23am

thanks.

anon68898643 · May 13, 2020, 10:13am

In the tester’s solution, what does it mean when the comment part says “taking all possible prefix of R” ?

kritidipto · May 13, 2020, 10:33am

No i think its fine.ur Z has 7 digits, in the explaination only 6 digits are there

rajkumar612 · May 13, 2020, 12:29pm

@harshil21 I am getting wrong answer now.Can you give me some testcases where i am getting wrong.
I had tried all the testcases mentioned here.Don’t know what i am missing

redoc_007 · May 13, 2020, 12:53pm

@harshil21 trying to solve subtask 2 getting WA
could you let me know which case I’m missing
tried test cases shared by you on this thread getting the expected output
solution url : CodeChef: Practical coding for everyone

harshit_kgupta · May 13, 2020, 1:33pm

@rajasalok1996 Though several 2^n-1 with bits greater than bits in x and y (in other words, simply greater in value than both x and y) will maximize F, we need to find minimum value of Z that minimizes the given expression.

harshil21 · May 13, 2020, 1:36pm

Just missing the last bits probably

2
318458 58156 0 28842
794296 28206 0 26

You are missing these cases.

harshit_kgupta · May 13, 2020, 1:46pm

@harshil21, first of all, nice editorial!
Can you please mention what range of numbers was used in the testcases due to which even a single testcase didn’t got executed within the time limit, leading to entire TLE and 0.0 score, for Brute-Force Approach.

Thanks!

zacros7 · May 13, 2020, 5:24pm

Hey @harshil21. Can you please review this and tell which test cases its failing?
https://www.codechef.com/viewsolution/33065603
Only for subtask 2.

redoc_007 · May 13, 2020, 5:26pm

Thanks! forgot to handle it

harshil21 · May 13, 2020, 5:44pm

Maybe your code would fail on higher case as you’ve not used 1LL or 1ll while shifting.
For. example:

(1 << 41) != (1LL << 41).

harshil21 · May 13, 2020, 5:45pm

Test data is generated randomly between the given constraints.
But I could see into it if you could provide me a link of the solution.

ac_boss · May 13, 2020, 5:57pm

Why can’t you guys put readable codes here in the editorials? With so many defines and functions, the code becomes very messy.

rajkumar612 · May 13, 2020, 6:04pm

@harshil21 CodeChef: Practical coding for everyone
Please look into my code
I had tried all the testcases memtioned here.All are giving correct aswers.But i am not getting AC.
Please give other test cases where i am failing

harshit_kgupta · May 13, 2020, 6:23pm

Thank you for an active invitation to help me with my code. Basically, I had just tried a brute force approach after optimising the low and high values aptly to some binary numbers of the form 2^n-1, assuming that minimum Z for maximum value of given equation will be within this range.

Though it worked for smaller custom inputs and the sample inputs that were given with the question, it was not even able to get any partial marking from the submission result.

In case you’d like to see the code, here’s the link to my bruteforce approach.
https://www.codechef.com/viewsolution/32482373

harshil21 · May 14, 2020, 5:04am

Try

1
154112 33236 0 462

The answer should be 0.

harshil21 · May 14, 2020, 5:06am

You can not loop from L to R as T ranges upto 10^5 and L,R \le 10^{12}.
You have to find a approach which solves the question through binary bits of the number.
Read the editorial.

harshil21 · May 14, 2020, 5:08am

I’ve tried to put up a very commented solution so it is very comprehensive for a reader.
The functions simplify the process.