## Search found 84 matches

- Tue Dec 17, 2013 6:44 pm
- Forum: Clarifications on Project Euler Problems
- Topic: Problem 011
- Replies:
**66** - Views:
**9317**

### Re: Problem 011

If you do that, you will definitely get the green tick.

- Tue Dec 03, 2013 8:52 pm
- Forum: News, Suggestions, and FAQ
- Topic: Errors/Warnings/Bugs
- Replies:
**539** - Views:
**129130**

### Re: Errors/Warnings/Bugs

wonderful

- Tue Dec 03, 2013 8:26 am
- Forum: News, Suggestions, and FAQ
- Topic: Errors/Warnings/Bugs
- Replies:
**539** - Views:
**129130**

### Re: Errors/Warnings/Bugs

Hello.

It's not a bug, but I use PE with lights turned off. The new Last 10 problems solved section on Progress page is a little invisible. Anyway it is a great idea and I love it.

Greetings,

TheEvil

It's not a bug, but I use PE with lights turned off. The new Last 10 problems solved section on Progress page is a little invisible. Anyway it is a great idea and I love it.

Greetings,

TheEvil

- Thu Nov 28, 2013 7:00 am
- Forum: Number
- Topic: Mathematics
- Replies:
**3** - Views:
**2526**

### Re: Mathematics

First of all, it is not an equation. But if you are intrested in the closed form of that series:

x*n - n*(n-1)*y/2

x*n - n*(n-1)*y/2

- Thu Nov 28, 2013 6:53 am
- Forum: Number Theory
- Topic: Sublattices in Z^2
- Replies:
**5** - Views:
**2911**

### Re: Sublattices in Z^2

Exercise 4 and 5 are exactly the same. x=y (mod 3) /multiply by 2 --- Exercise 5 2x=2y (mod 3) --- Exercise 4 If you like the coset language, then let the set given in Exercise 5 be A. The nine cosets in Z 2 : A (1,0)A (2,0)A (0,1)A (1,1)A (2,1)A (0,2)A (1,2)A (2,2)A That's why you get 9, as the ind...

- Tue Nov 26, 2013 6:59 pm
- Forum: Number Theory
- Topic: Sublattices in Z^2
- Replies:
**5** - Views:
**2911**

### Re: Sublattices in Z^2

When I hear the word lattice, I always think of the algebraic structure, with meet and join operation. You can read about them in wikipedia, and a lot of other books, maybe in general introductions to algebra.

Wikipedia link:

http://en.wikipedia.org/wiki/Lattice_%28order%29

Wikipedia link:

http://en.wikipedia.org/wiki/Lattice_%28order%29

- Tue Nov 26, 2013 6:44 am
- Forum: Number Theory
- Topic: Sublattices in Z^2
- Replies:
**5** - Views:
**2911**

### Re: Sublattices in Z^2

1. not sublattice, since (1,0)+(0,1) is not belong to the set the others are sublattices with indeces: 2. infinity 3. two 4. nine 5. nine, this is the same sublattice as in example 3 I'm nor sure totally, since your definition of sublattice seems a little wierd to me. Any definition, which does not ...

- Thu Nov 21, 2013 4:04 pm
- Forum: Number Theory
- Topic: Mathematicians Team Up To Close the Prime Gap
- Replies:
**2** - Views:
**2257**

### Re: Mathematicians Team Up To Close the Prime Gap

You misread a quantor. Not all prime neighbours have distance less than 70 million, but there exists infinetely many prime numbers, for which the distance between them is less than 70 million. Zhang's result is incredibly amazing, since no one was ever this close to the twin primes conjecture. You h...

- Wed Nov 20, 2013 5:50 am
- Forum: Number
- Topic: Primitive root
- Replies:
**1** - Views:
**2710**

### Re: Primitive root

I don't know how much do you know about field theory, but the most simple way to prove it, is to use field theory. Every Z p is a finite field. If you leave 0 out, and take only the multiplication, you get a cyclic group of order p-1. It is not trivial, but from this it is easy to prove. Z p x (the ...

- Sat Nov 16, 2013 9:23 am
- Forum: News, Suggestions, and FAQ
- Topic: Level 17?
- Replies:
**5** - Views:
**2011**

### Re: Level 17?

I don't think you can do that. But you can add this to your signature:

http://projecteuler.net/profile/ving.png

http://projecteuler.net/profile/ving.png

- Thu Nov 14, 2013 7:25 am
- Forum: Clarifications on Project Euler Problems
- Topic: Problem 359
- Replies:
**13** - Views:
**4579**

### Re: Problem 359

You should always check everyone wit the last occupied room on every floor. For Person 4, you should check 4+3=7 instead of 4+1=5. Then do it for floow 2, and so on.

- Wed Nov 06, 2013 6:36 pm
- Forum: Clarifications on Project Euler Problems
- Topic: Problem 027
- Replies:
**25** - Views:
**7415**

### Re: Problem 027

If you feed positive numbers in the polynom n

^{2}+an+b, it is the same as feeding negative numbers in n^{2}-an+b. So the problem won't be easier and the only change would be in the sign of the answer. Anyway you will get the correct answer for increasing numbers.- Sun Oct 20, 2013 7:20 pm
- Forum: Combinatorics
- Topic: Simple Antichain Question
- Replies:
**1** - Views:
**2084**

### Re: Simple Antichain Question

I'm supposing that P(n) is the power set of an n element set in this comment. I don't think that this queation is simple. The upper bound for an antichain is reached at [n/2], and called Sperner theorem. See at the end of this:http://mathworld.wolfram.com/Antichain.html I have seen the proof of this...

- Sun Sep 29, 2013 9:33 pm
- Forum: Clarifications on Project Euler Problems
- Topic: Problem 142
- Replies:
**16** - Views:
**6509**

### Re: Problem 142

The correct answer is lower than yours. It has the same number of digits as yours.

By the way: you can check any of your answers easily with a calculator, the hard part is to find the smallest one.

By the way: you can check any of your answers easily with a calculator, the hard part is to find the smallest one.

- Wed Sep 18, 2013 4:15 pm
- Forum: Programming languages
- Topic: in C: Optimal way to measure elapsed time?
- Replies:
**2** - Views:
**7930**

### Re: in C: Optimal way to measure elapsed time?

I've stolen this from someone from a post thread. It's basically the same, but you can control when to start the timer. #include <time.h> clock_t start; //declaration of time type variable int main(){ start=clock(); /* Your program goes here*/ printf("Time: %f sec",(double)(clock()-start)/CLOCKS_PER...

- Thu Jul 25, 2013 6:11 am
- Forum: Clarifications on Project Euler Problems
- Topic: Problem 003
- Replies:
**128** - Views:
**43728**

### Re: Problem 003

If you do it properly, you have to know only that 3 is the smallest odd prime number. You don't have to know any other prime numbers. Maybe it doesn't help you, but it's the key idea.

- Tue Jul 23, 2013 7:52 pm
- Forum: Clarifications on Project Euler Problems
- Topic: Problem 003
- Replies:
**128** - Views:
**43728**

### Re: Problem 003

When I did it I used 32 bit integers. It was a lot more complicated than with 64 bit integers. That is trivial if you have the necessary idea.

- Tue Jul 23, 2013 6:08 pm
- Forum: Clarifications on Project Euler Problems
- Topic: Problem 003
- Replies:
**128** - Views:
**43728**

### Re: Problem 003

Since you are looking for prime factors, why don't you try to factorize it, instead of checking every prime number. I think this hint should be enough.

- Thu Jul 11, 2013 6:56 am
- Forum: Clarifications on Project Euler Problems
- Topic: Problem 143
- Replies:
**26** - Views:
**9968**

### Re: Problem 143

@karluk

Sorry I didn't see that, I thought the your problem was with X and T. Sorry again.

Sorry I didn't see that, I thought the your problem was with X and T. Sorry again.

- Wed Jul 10, 2013 4:11 pm
- Forum: Clarifications on Project Euler Problems
- Topic: Problem 143
- Replies:
**26** - Views:
**9968**

### Re: Problem 143

There appears to be a minor discrepancy between the statement of problem 143 and the accompanying diagram. The statement of the problem says XB = q, and XC = r for any point X in triangle ABC. But the diagram labels TC = q and TB = r for the Torricelli point. In order to be consistent with the stat...