Find product of prime numbers between 1 to n in C++

C++Server Side ProgrammingProgramming

Suppose we have a number n. We have to find the product of prime numbers between 1 to n. So if n = 7, then output will be 210, as 2 * 3 * 5 * 7 = 210.

We will use the Sieve of Eratosthenes method to find all primes. Then calculate the product of them.

Example

 Live Demo

#include<iostream>
using namespace std;
long PrimeProds(int n) {
   bool prime[n + 1];
   for(int i = 0; i<=n; i++){
      prime[i] = true;
   }
   for (int i = 2; i * i <= n; i++) {
      if (prime[i] == true) {
         for (int j = i * 2; j <= n; j += i)
         prime[j] = false;
      }
   }
   long product = 1;
   for (int i = 2; i <= n; i++)
   if (prime[i])
      product *= i;
   return product;
}
int main() {
   int n = 8;
   cout << "Product of primes up to " << n << " is: " << PrimeProds(n);
}

Output

Product of primes up to 8 is: 210
raja
Published on 18-Dec-2019 17:27:57
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