Project Euler Forum

StephanKoehler wrote: ↑Mon Jan 11, 2021 4:56 pm I just want to point out that the given solution of four primes [3, 7, 109, 673] is actually wrong. The following sequence meets the criteria and has a lower sum [7, 9, 19, 433].
Nonetheless, using the same algorithm I was able to get the correct answer for five primes.

9 is not prime

If this helps, the expected distance means the expected value of the distance. I believe it is also assumed that each drone is equally likely to be chosen each second.

Just checked in Chrome and it worked fine for me. I do notice something odd though. There's no arrows for the next and previous problems. Is that only available when logged in for some reason?

I assume you used some sort of program to find the sequences and didn't just do 400 by hand. Did you also try a similar program for t(6)? If that fails, you might be able to see where it's failing.

Problem 710 celebrates PE membership first exceeding one million, earlier this year... When I add up the Statistics/Levels memberships on PE.net I get about 120,000 members... Does that mean there are about 900,000 members who Have solved 0 to 24 problems? From the statistics main page I see There ...

Can you tell me if my understanding of the problem is correct? Consider the following example: Suppose the original plain text was "HELLO WORLD", and the encryption key I chose was "97, 98, 99", which are the ascii values for a, b, c, respectively. To encrypt the plain text &quo...

I seem to be having an issue on this problem. I'm getting the correct answer for S(1000), but my answer is not being accepted for S(1,000,000). I've double and triple-checked my constants and created 3 extra loops to verify values used to calculate N(1,000,000). All 3 loops cleared without reporting...

Site's been down a lot today. Keeping this brief in case...

I appear to be unable to delete private messages. I mark 2 of them, select "Delete marked" and click "Go". I get a message saying "The submitted form was invalid. Try submitting again."

From https://en.wikipedia.org/wiki/Series_and_parallel_circuits In a series circuit, every device must function for the circuit to be complete. If one bulb burns out in a series circuit, the entire circuit is broken. From this problem: The electrical system uses two fuses in series,... For the heati...

I believe the N fuses are replacements. The only circuit has 2 fuses in series. Choose 2 replacements and, if both fuses are good, there's a closed circuit and everything works. Otherwise, there's no power. He keeps trying a different pair until he finds a pair that works.

I don't think people often return to the solution threads. What I've done in the past is ask the question in the solutions thread, then post a message in these forums directing people to the question.

Got it. That's the part I was missing. Thanks.

Am I missing something here? Let's say n=1. Oscar writes "10". Eric can't write any number without exceeding 2. There is one 1. Oscar wins. Yet in the problem statement, Eric guarantees a win.

DanielJackson wrote: ↑Wed Feb 19, 2020 11:28 pm n = a*b, a > b
Let n = 15 = 15*1 = 5*3
1. a = 15, b = 1 => d = 4, 19^2 - 15^2 - 11^2 = 15
2. a = 5, b = 3 => d = 2, 7^2 - 5^2 - 3^2 = 15
n = 15 has exactly 2 solutions and 15 < 27 (by condition). Where am I wrong?

$5^2-3^2-1^2=15$. 15 has at least 3 solutions.

I probably should have noted when this happened, but one of my last times attempting to access the forums, I instead got something on the bottom of the screen asking "What do you want to do with index.php?", giving me the option to open, save, or cancel. And now when I try to pin or unpin ...

What "new plates"? You take n plates and divide them into k piles. For each calculation of f(n,k), the total number of plates is fixed.

I think the way the sentence is structured can cause confusion. Namely

a 31K text file containing a 80 by 80 matrix, from the left column to the right column.

This could be interpreted to mean the matrix is given one column at a time.

This site's been down quite a bit lately it seems. Some sort of SQL error, not always the same each time.

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 ...