Problem 669

A place to air possible concerns or difficulties in understanding ProjectEuler problems. This forum is not meant to publish solutions. This forum is NOT meant to discuss solution methods or giving hints how a problem can be solved.
Forum rules
As your posts will be visible to the general public you
are requested to be thoughtful in not posting anything
that might explicitly give away how to solve a particular problem.

This forum is NOT meant to discuss solution methods for a problem.

In particular don't post any code fragments or results.

Don't start begging others to give partial answers to problems

Don't ask for hints how to solve a problem

Don't start a new topic for a problem if there already exists one


See also the topics:
Don't post any spoilers
Comments, questions and clarifications about PE problems.
Post Reply
crb11
Posts: 2
Joined: Fri Nov 17, 2017 2:29 pm

Problem 669

Post by crb11 » Mon May 13, 2019 9:24 pm

I've come up with what I thought was a unique solution for the n=34 case, but I don't have knight 30 sitting in the 3rd chair from the king's left. My solution starts 4-30-25-9-12-... (not posting it all as I think it may give away the pattern needed to solve the puzzle). Any pointers people can give me? I'd be surprised if an error had got through this far, although there's still a typo in the text: "the king always prefers an arrangement where the knight to the his left". Thanks in advance.

crb11
Posts: 2
Joined: Fri Nov 17, 2017 2:29 pm

Re: Problem 669

Post by crb11 » Mon May 13, 2019 10:08 pm

Ok, I'm stupid. (I'd not realised I hadn't used all the numbers.) I now have a solution which fits the rubric.

Shogimoto
Posts: 1
Joined: Tue May 14, 2019 12:49 pm

Re: Problem 669

Post by Shogimoto » Tue May 14, 2019 12:51 pm

Ask me again about Problem 669 in the year 2040 again. I have an alogorithm, but it will run for 20 years until it prints the solution. I hope I do not run into any date problems during the wait.

Oh, I am lucky, i made an error in judging the situation: I will have the solution already in 1.92 years :-)

mdean
Posts: 154
Joined: Tue Aug 02, 2011 1:05 am

Re: Problem 669

Post by mdean » Mon Sep 23, 2019 7:44 am

At this point, I'm about 1 step away from challenging the answer to this problem. I know a fair number of people have already solved this problem. I know I have everything in correctly, the program appears to operate just fine. I've done just about everything I can. Next step is to verify each step by calculator. If that checks, I'll find someone to pm to plead the best case for my answer being correct.
Image

User avatar
RobertStanforth
Administrator
Posts: 1117
Joined: Mon Dec 30, 2013 11:25 pm

Re: Problem 669

Post by RobertStanforth » Mon Sep 23, 2019 5:31 pm

mdean wrote:
Mon Sep 23, 2019 7:44 am
At this point, I'm about 1 step away from challenging the answer to this problem. I know a fair number of people have already solved this problem. I know I have everything in correctly, the program appears to operate just fine. I've done just about everything I can. Next step is to verify each step by calculator. If that checks, I'll find someone to pm to plead the best case for my answer being correct.
I sent you a PM.

mdean
Posts: 154
Joined: Tue Aug 02, 2011 1:05 am

Re: Problem 669

Post by mdean » Tue Sep 24, 2019 7:50 pm

The program was working correctly. All the hand calculations were correct. One simple mistake on a limit of summation threw everything else off. My thanks to RobertStanforth for lending an ear. If I hadn't had to lay everything out to someone else, regardless of whether or not he actually reads all that, I would have been hard pressed to locate the mistake.
Image

Post Reply