Question

Exercise 3: Write a program that reads a positive number and checks if the number can be expressed as a sum of two prime numbers. If yes, write all possible ways of expressing the number as sum of primes. Note: n is a prime if it is divisible only by 1 and itself, hence not divisible by any integer in the range from 2 to sqrt(n), both inclusive. Write a function is Prime that take a positive number returns true if the number is prime, else return false. Use isPrime function to perform the task of writing all possible ways of expressing the number as sum of primes. x CA. C:\Windows\system32\cmd.exe Enter a positive integer: 96 13 + 83 2 + 29 + 23

use simple C++ please

Answer 1

// Please refer to the screenshot of the code to understand indentation

#include <iostream>
#include <cmath>
using namespace std;

// isPrime(x) checks if x is prime or not. It returns false if it is not prime, and returns true otherwise.
bool isPrime(int x)
{
   int lowerLimit = 2;
   int upperLimit = sqrt(x);
   for(int i = lowerLimit; i<=upperLimit; i++)
   {
       if(x%i==0)
           return false;
   }
   return true;
}

int main()
{
   // Take an integer as user input
   cout<<"Enter a positive integer: ";
   int n;
   cin>>n;
  
   // We check if the inputted integer can be expressed as sum of two prime numbers, only upto its half (n/2), to avoid repetitions.
   int lowerLimit = 1;
   int upperLimit = n/2;
   for(int i = lowerLimit; i<=upperLimit; i++)
   {
       if(isPrime(i)==true)
       {
           int difference = n-i;
           if(isPrime(difference)==true)
           {
               cout<<n<<" = "<<i<<" + "<<difference<<endl;
           }
       }
   }
}

PrimeSum.cpp #include <iostream> #include <cmat h> 2 using namespace std 4 //isPrime(x) checks if x is prime or not. It returns false if it is not prime, and returns true otherwise. bool isPrime (int x) 7E 6 int lowerLimit = 2; int upperLimit sqrt(x); for (int i lower Limit; i<=upperLimit; i+ { if (xi0) 8 10 11 12 return false; } return true; } 14 15 16 17 int main) 18 19 // Take an integer as user input cout<<"Enter a positive integer: "; int n cin>>n; 20 21 22 // We check if the inputted integer can be expressed as sum of two prime numbers, only upto its half (n/2), to avoid repetitions. int lowerLimit = 1; int upperLimit = n/2; for (int i= 1ower Limit; i<=upperLimit; i++ { if (is Prime (i ) ==true) 28 29 int difference = n-i if (is Prime (difference) = =true) 33 cout<<n<<" = "<<i<<" + "<«difference<<endl; 38 39

Enter a positive integer: 96 96 = 7 + 89 96 96 96 96 13 + 83 = 17 + 79 = 23 +73 = 29+67 = 96 37 + 59 96 = 43 + 53

Enter a positive integer: 288 288 :5 + 283 = 288 7 + 281 = 288 = 11 + 277 288 = 17 + 271 288 31 257 288 288 59 229 288 288 288 = 19 + 269 288 37 + 251 47 + 241 288 61+227 89 + 199 97+ 191 288 288 288 288 288 107 + 181 109+ 179 131 157 = 137 + 151 = 139 + 149