primes

How to make a function in c++ to determine if two entered numbers are relatively prime (no common factors)? For example "1, 3" would be valid, but "2, 4" wouldn't. TonyK Galvanised into action by Jim Clay's incautious comment, here is Euclid's algorithm in six lines of code: bool RelativelyPrime (int a, int b) { // Assumes a, b > 0 for ( ; ; ) { if (!(a %= b)) return b == 1 ; if (!(b %= a)) return a == 1 ; } } Updated to add: I have been out-obfuscated by this answer from Omnifarious , who programs the gcd function thus: constexpr unsigned int gcd(unsigned int const a, unsigned int const b) {

This question already has answers here : Simple Prime Generator in Python (23 answers) Closed 5 years ago . I'm trying to write a generator function for printing prime numbers as follows def getPrimes(n): prime=True i=2 while(i<n): for a in range(2,i): if(i%a==0): prime=False break if(prime): yield i However I'm not getting the desired results p=getPrimes(100) should give me a generator function that will iterate primes from 2 through 100 but the result I'm getting is [2,3]. What am I doing wrong? You need to reset prime to True as the first statement inside the while block, not before it. As

I want to print all prime numbers that are 2-digits long. Here is my code: for(int input = 11; input <= 99; input += 2){ for(int x = 2; x < (int)Math.sqrt(input) + 1; x++){ if(input%x != 0){ System.out.println(input); break; }else{ break; } } } The problem is that it prints numbers like 35 or 49 which are not prime numbers. This works. You can see the output here . public class Main { public static void main(String[] args) { for(int input = 11; input <= 99; input += 2){ boolean found = false; for(int x = 2; x < (int)Math.sqrt(input) + 1; x++){ if(input%x == 0){ found = true; break; } } if(

The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143? I solved this problem on Project Euler my own way, which was slow, and then I found this solution on someone's github account. I can't figure out why it works. Why are a number of factors removed, equal to an index? Any insight? def Euler3(n=600851475143): for i in range(2,100000): while n % i == 0: n //= i if n == 1 or n == i: return i This function works by finding successive factors of its input. The first factor it finds will necessarily be prime. After a prime factor is found, it

This question already has answers here : Closed 6 years ago . Possible Duplicate: A number as it’s prime number parts I have this homework assignment of mine, hard as hell, where I have to get all the distinct prime partitions of a given number. For example, number 7 has five different prime partitions (or five different ways of representing the 2 prime partitions it has): 5 + 2 2 + 5 3 + 2 + 2 2 + 3 + 2 2 + 2 + 3 As you can see, the number itself is excluded in the case it's a prime. I don't have to print all the distinct partitions, only the number of them. So I'm a bit lost with this. I've

Here is the problem ( Summation of Four Primes ) states that : The input contains one integer number N (N<=10000000) in every line. This is the number you will have to express as a summation of four primes Sample Input: 24 36 46 Sample Output: 3 11 3 7 3 7 13 13 11 11 17 7 This idea comes to my mind at a first glance Find all primes below N Find length of list (.length = 4) with Integer Partition problem (Knapsack) but complexity is very bad for this algorithm I think. This problem also looks like Goldbach's_conjecture more. How can I solve this problem? This problem has a simple trick. You