## Search found 108 matches

- Mon Oct 13, 2003 5:35 pm
- Forum: Volume 101 (10100-10199)
- Topic: 10168 - Summation of Four Primes
- Replies:
**51** - Views:
**20229**

Dominik, can you describe in detail how your algorithm works? I still don't understand your method... If you want to find two primes k and l such that k + l = N, then at least one of them has to be bigger than (or equal to) N, right? So if I know primes up to sqrt(N) only, what does it help me? Of c...

- Mon Oct 13, 2003 5:28 pm
- Forum: Other words
- Topic: Why do people use topic number (only) as subject?
- Replies:
**3** - Views:
**892**

I totally agree with you, it is a lot of work to find out what problem the question is about. Also, I think that people should not just post their code without a thorough explanation of what you are doing. I am willing to help anyone who has problems, but please agree to those rules. Also, some peop...

- Sat Oct 11, 2003 7:41 pm
- Forum: Volume 4 (400-499)
- Topic: 453 - Intersecting Circles
- Replies:
**84** - Views:
**15132**

- Sat Oct 11, 2003 7:39 pm
- Forum: Volume 102 (10200-10299)
- Topic: 10298 - Power Strings
- Replies:
**31** - Views:
**13407**

- Sat Oct 11, 2003 9:23 am
- Forum: Volume 101 (10100-10199)
- Topic: 10168 - Summation of Four Primes
- Replies:
**51** - Views:
**20229**

- Thu Oct 09, 2003 5:21 pm
- Forum: Volume 101 (10100-10199)
- Topic: 10168 - Summation of Four Primes
- Replies:
**51** - Views:
**20229**

I still don't understand. I assume your code would look something like this then (pseudocode): if( n%2 == 0 ) write "2 2"; n = n-4; if( n%2 == 1 ) write "2 3"; n = n-5; // now n is even so it can be written as the sum of two primes for( int i=2; i<n; i++ ) if( prime[i] && prime[n-i] ) write i, n+i; ...

- Thu Oct 09, 2003 10:54 am
- Forum: Volume 101 (10100-10199)
- Topic: 10168 - Summation of Four Primes
- Replies:
**51** - Views:
**20229**

- Thu Oct 09, 2003 12:18 am
- Forum: Volume 1 (100-199)
- Topic: 102 - Ecological Bin Packing
- Replies:
**485** - Views:
**50081**

- Wed Oct 08, 2003 9:25 pm
- Forum: Volume 101 (10100-10199)
- Topic: 10168 - Summation of Four Primes
- Replies:
**51** - Views:
**20229**

this problem is very easy if you know the following almost-theorem (the Goldbach Conjecture): Every even number >= 4 can be written as the sum of two primes My program ran in 1.5 seconds however; so it's pretty slow.. At the moment I'm precalculating primes up to 10000000 using the famous siff, and ...

- Wed Oct 08, 2003 8:38 pm
- Forum: Volume 1 (100-199)
- Topic: 133 - The Dole Queue
- Replies:
**42** - Views:
**5746**

try the input and output at http://contest.mff.cuni.cz/archive/nzl1990a/

- Wed Oct 08, 2003 8:36 pm
- Forum: Volume 1 (100-199)
- Topic: 102 - Ecological Bin Packing
- Replies:
**485** - Views:
**50081**

- Wed Oct 08, 2003 2:14 pm
- Forum: Volume 104 (10400-10499)
- Topic: 10427 - Naughty Sleepy Boys
- Replies:
**35** - Views:
**21242**

- Wed Oct 08, 2003 11:14 am
- Forum: Volume 1 (100-199)
- Topic: 133 - The Dole Queue
- Replies:
**42** - Views:
**5746**

- Wed Oct 08, 2003 11:12 am
- Forum: Volume 1 (100-199)
- Topic: 113 - Power of Cryptography
- Replies:
**162** - Views:
**16241**

- Tue Oct 07, 2003 11:25 pm
- Forum: Algorithms
- Topic: One interesting geometry problem...... Help me to solve it
- Replies:
**13** - Views:
**3282**