Project Euler Forum

Like v6ph1 said, if you are looking for online compilers, repl is my favourite..

I changed the code to remove the loop-checking and use modified-step values but still no improvements in timing. For example, the mod-2 version takes ~ 75 secs to list all primes upto 10^8, the mod-6 version takes ~ 85 secs whereas the step-adjusted-mod-6 version takes ~ 95 secs. step-adjusted-mod-6...

Thanks v6ph1. I too arrived at the same loop for making the program slow. But I think it may be slightly different. Rather than the loop checking, I think the runs more often as the chance of hitting the numbers with mod in the given set becomes low. That I think is the trade-off in the higher mod v...

Hi all, I recently saw a post on an Infinite Prime Number Generator on Stack Exchange given below. from itertools import count from timeit import default_timer start = default_timer() # ideone.com/aVndFM def postponed_sieve(): # postponed sieve, by Will Ness for c in (2, 3, 5, 7): # original code Da...

@ jaap , I think you did all the heavy lifting leaving just the algebra to me. The key to solving this problem is to pick the 'central angle' as the variable of interest. Though the 'cubic' approach ended nowhere, it reminded me of the trick of evaluating $\sin(\pi/5)$ exactly, which I kinda used to...

... It is straightforward to see that: A1A2 = 2sin(x) A1A3 = 2sin(2x) A1A4 = 2sin(3x) From here, we have, $\displaystyle\frac{1}{\sin x}=\frac{1}{\sin 2x}+\frac{1}{\sin 3x}$ $\displaystyle\sin 2x=\frac{\sin x \sin 3x}{\sin 3x-\sin x}=\frac{\sin x \sin 3x}{2\sin x-4 \sin^3 x}=\frac{\sin x\sin 3x}{2 ...

Hi All, This post is about an analysis of a game described in Goldratt's best seller 'The Goal'. The game is as follows: Consider $b$ bins of infinite capacity in a row with an imaginary Source of infinite matchsticks. Matchsticks are transferred to the bins in the following manner: For every bin, m...

merlinnimue wrote: ↑

Mon Apr 30, 2018 5:08 pm

Quick sanity check: can anyone confirm if S(10^6) =xxxxxxxxxxxxxxx?

We are not supposed to post partial answers in this forum. But anyway, the value you posted seems to be wrong. Happy solving!!

A suggestion on awards.. Is there a possibility of introducing country-wise awards.. Something like 'First in your country', 'Top solver of your country' and something like that?? The Elite group is highly competitive to even make an attempt at getting some awards like 'The Gold Medal'. Would probab...

Thank you all.. Solved it... For someone who didn't study computer science, the whole problem seemed very convoluted but fortunately the structure of the problem was quite simple.. One more thing.. Should the number of solvers be hidden until we solve a problem? At least recently for me, I'm taking ...

Scoping in lambda calculus works very much like in C-family languages. Consider these two lines of pseudo-code: { string x = "foo"; { string y = "bar"; print(x, y); } } { string x = "foo"; { string x = "bar"; print(x, x); } } They are not equivalent, because the first one prints "foo bar" and the s...

traxex wrote: ↑

Thu Mar 15, 2018 5:35 am

MuthuVeerappanR wrote: ↑

Thu Mar 15, 2018 4:08 am

lately many problems seems solvable-within-a-minute in C, C++ mostly.

Can you give some examples?

Problem 614 (View Problem) and Problem 611 (View Problem) I think..

The choice of programming language is tough problem by itself in PE. Probably, the best answer would be, 'No one programming language can solve all the problems equally well'. I've seen many MATLAB solutions in the 400- problems, but lately many problems seems solvable-within-a-minute in C, C++ most...

The question introduces $c, s, p$ and $q$ as circumference of the circles but in the second para says they are the numbers of teeth. Am confused about the interpretation of these values in the final summation. I'm already confused about whether the 'module' is something implicitly given or not? Many...

Kudos to the collapse idea. Thanks euler.

euler,
The overall progress bar changes from red to green whereas the progress bar of the difficulty levels change from red to orange. Would be nice if both of them convey the same meaning. #suggestion

I did it!!! Yes!!! In your face Problem 566 (View Problem)!!!

Whoah.. Me again!! I don't know about other sovlers, but if you can send me a mail about the spoilers I left on a problem thread, I can hide it myself.. I have over 200 posts.. I don't think I'll be able to go over it all.. Thanks.

This thread is about my post in 586 I think. I apologize for spoiling the problem for anyone but when I was making the post, I thought solvers would enjoy the connection between the said problems. Concern was raised in the forum itself and now the problem numbers are hidden. But I always feel good a...

I'm not expert in DP either but this problem can be solved in a couple of ways. The problem at hand is well known and studied. You are asking for the number of partitions with distinct summands. My favorite would be to use generating functions. Let $f(x)=(1+x)(1+x^2)(1+x^3)(1+x^4)\cdots$ What does t...