I want to print the first 10000 prime numbers. Can anyone give me the most efficient code for this? Clarifications: It does not matter if your code is inefficient for n >10000. The size of the code does not matter. You cannot just hard code the values in any manner. ...
Alright, so maybe I shouldn't have shrunk this question sooo much... I have seen the post on the most efficient way to find the first 10000 primes. I'm looking for all possible ways. The goal is to have a one stop shop for primality tests. Any and all tests people know for finding prime numbers are welcome. And so: What are all the...
What is the best approach to calculating the largest prime factor of a number? I'm thinking the most efficient would be the following: Find lowest prime number that divides cleanly Check if result of division is prime If not, find next lowest Go to 2. I'm basing this assumption on it being easier to calculate the small prime factors...
I'm going through the problems on projecteuler.net to learn how to program in Erlang, and I am having the hardest time creating a prime generator that can create all of the primes below 2 million, in less than a minute. Using the sequential style, I have already written three types of generators, including the Sieve of Eratosthenes, and ...
('1' * N) !~ /^1?$|^(11+?)\1+$/ On the net, I found this piece of Ruby code that works for N >= 0 that determines whether or not N is a prime. From what I can tell, it looks like play with regex but I have no idea how it works. Could someone tell me how it works? ...
I have been trying to work my way through Project Euler, and have noticed a handful of problems ask for you to determine a prime number as part of it. 1) I know I can just divide x by 2, 3, 4, 5, ..., square root of X and if I get to the square root, I can (safely) assume that the number is prime. Unfortunately this solution seems quite...
I'm trying to work through Project Euler and I'm hitting a barrier on problem 03. I have an algorithm that works for smaller numbers, but problem 3 uses a very, very large number. Problem 03: The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143? Here is my solution in C# and it's b...
Is this seen as an in efficient prime number generator. It seems to me that this is pretty efficient. Is it the use of the stream that makes the program run slower? I am trying to submit this to SPOJ and it tells me that my time limit exceeded... #include <iostream> #include <sstream> using namespace std; int main() { int testCa...
Omitting details of methods to calculate primes, and methods of factorisation. Why bother to factorise ? What are its applications ? ...
I have a range of random numbers. The range is actually determined by the user but it will be up to 1000 integers. They are placed in this: vector<int> n and the values are inserted like this: srand(1); for (i = 0; i < n; i++) v[i] = rand() % n; I'm creating a separate function to find all the non-prime values. Here is what I...
We're having a bit of fun here at work. It all started with one of the guys setting up a Hackintosh and we were wondering whether it was faster than a Windows Box of (nearly) same specs that we have. So we decided to write a little test for it. Just a simple Prime number calculator. It's written in Java and tells us the time it takes to ...
A few years ago, it was proven that PRIMES is in P. Are there any algorithms implementing their primality test in Python? I wanted to run some benchmarks with a naive generator and see for myself how fast it is. I'd implement it myself, but I don't understand the paper enough yet to do that. ...
As a Christmas gift I have written a small program in Java to calculate primes. My intention was to leave it on all night, calculating the next prime and writing it to a .txt file. In the morning I would kill the program and take the .txt file to my friend for Christmas. Is there anything I should be worried about? Bear in mind that thi...
I need to find out the prime factors of over 300 billion. I have a function that is adding to the list of them...very slowly! It has been running for about an hour now and i think its got a fair distance to go still. Am i doing it completly wrong or is this expected?! (Please no solutions for my code to give it away, but some subtle hi...
One thing that always strikes me as a non-cryptographer: Why is it so important to use Prime numbers? What makes them so special in cryptography? Does anyone have a simple short explanation? (I am aware that there are many primers and that Applied Cryptography is the Bible, but as said: I am not looking to implement my own cryptographic...
Which is the fastest algorithm to find out prime numbers using C++? I have used sieve's algorithm but I still want it to be faster! ...
Hi, I'm currently trying out some questions just to practice my programming skills. ( Not taking it in school or anything yet, self taught ) I came across this problem which required me to read in a number from a given txt file. This number would be N. Now i'm suppose to find the Nth prime number for N <= 10 000. After i find it i'm supp...
Hi, could someone please tell me what I'm doing wrong with this code. It is just printing 'count' anyway. I just want a very simple prime generator (nothing fancy). Thanks a lot. lincoln. import math def main(): count = 3 one = 1 while one == 1: for x in range(2, int(math.sqrt(count) + 1)): if count % x == 0: ...
Hi all, I've been trying to work my way through Problem 27 of Project Euler, but this one seems to be stumping me. Firstly, the code is taking far too long to run (a couple of minutes maybe, on my machine, but more importantly, it's returning the wrong answer though I really can't spot anything wrong with the algorithm after looking thr...
like 17, is a prime, when reversed, 71 is also a prime. We manage to arrive at this code but we cant finish it. #include <stdio.h> main() { int i = 10, j, c, sum, b, x, d, e, z, f, g; printf("\nPrime numbers from 10 to 99 are the follwing:\n"); while (i <= 99) { c=0; for (j = 1; j <= i; j++) {...