Project Euler Forum

Background I came across this interesting stack overflow question: https://stackoverflow.com/questions/47111546/finding-smallest-subarray-lengths-for-given-multiple-queries#comment81192683_47111546 Question There is an array n = 1 million in length containing positive integers. There are also n = 1...

Can you also give the value for g(1)?

I am not sure from the problem statement whether g(1) should be 0 or 1?

I've just enjoyed solving problem 459 (after a year and a bit) but noticed a slightly curious thing when looking to see how quickly others had managed to solve it: The fastest solvers list for Problem 459 only mentions 61 people, while the archives page lists 114 people as having solved it. Is this ...

I have been struggling to solve a problem from CodeForces involving the optimal strategy for a two player game played on a tree. (This is a problem from a finished contest - but no editorial has been published yet as far as I can see.) I have put a description of the problem on Stack Overflow http:/...

Incidentally, I notice that I have now lost my perfection badge

I guess the system spotted I have been getting lazy recently and not attempting many problems...

I was just wondering whether it would be good to note somewhere who suggested each problem? It might show a bit of appreciation to those able to come up with the problems, and solvers might be able to start recognising the names of problem setters whose questions they enjoy, perhaps helping them whe...

For what it's worth, I would prefer there not be such limits before people can solve recent problems. If I recommend Project Euler to someone who wants to learn a new language then I suggest starting from the easiest problems, but if someone just wants to have fun and play with solving some mathemat...

I wonder if you are thinking about the problem like a game where Jeff is choosing where to make the cuts? In this case you are correct, and Jeff can "win" the game on his first move by cutting off most of the cake. However, this is not the intention of the problem. It is better to think of it as a s...

I use this kind of metaprogramming quite often when I need to write in hardware description languages (such as Verilog or VHDL) because these languages are relatively verbose. However, my preferred direction is opposite to yours - I tend to write Python code to generate the RTL output. I find my met...

One argument is that air resistance will increase non-linearly with speed, so the ball going through the trough might be expected to be faster and meet with more air resistance, and come out slower.

However, this is likely to be a negligible effect so probably the proper answer is something else?

Welcome! In Project Euler you just need to submit the numerical answer not the code. Type the answer you found in the box labelled Answer. Type the 5 digit number shown in the image in the box labelled Confirmation Code. Press the Check button. You will then get a green tick (if the answer is right)...

There are some good tutorial articles at http://community.topcoder.com/tc?module=Static&d1=tutorials&d2=alg_index . It is also worth reading the editorials for past competitions as these contain worked solutions for all their competition problems. http://apps.topcoder.com/wiki/display/tc/Algorithm+P...

I also misread the question initially so here is a clarification that would have helped me and I hope is not considered to spoil the question. Suppose A has a probability of 20% of winning, and a probability of 10% of losing, and there is a 70% probability of a draw. In this case A does NOT have a >...

The sum does not have to start with 2.

e.g. 7+11+13 = 31 would be another example.

Works for me now.

Same for me, perhaps someone could post the problem here if they can see it?

Thank you very much for your reply, this satisifes my curiosity. (Although I was kind of hoping that someone had suggested a problem (and worked solution) along the lines "What is the smallest N such that if the integers {1, 2, ..., N} are colored, each with one of 2 different colors, then there are...

Out of curiosity I was wondering how often the Project Euler team comes across a question that: 1) is interesting and easy to explain 2) has a nice simple solution (e.g. 15 lines of Python) 3) is considered too hard to be used as a Project Euler problem(!) It is simple enough to find questions that ...

Curiously, according to http://projecteuler.net/award=22;page=20 someone called oldjales has this award despite only having solved a single problem, so perhaps the award just depends on one particular solution?

You may want to consider this factorisation: z^2 = 1 +cx cx=z^2-1 cx=(z-1)(z+1) For example, suppose c is a prime p. => p|(z-1) or p|(z+1) =>z=kp+1 or z=kp-1 gives all the solutions. (Solutions for x given by x=(z-1)(z+1)/c) If c is composite, then you could consider all factorisations c=a.b You can...