# SNOWPRIM-editorial

CAKEWALK

### PREREQUISITES:

Math, Prime Numbers

### PROBLEM:

Given a number n you need to tell if 2*n can be written as some of two primes.

### EXPLANATION:

Observe that 2n will always be an even number. According to the even Goldbach conjecture (Euler, 1742) all even numbers larger than 2 are the sum of two primes. This conjecture is unsolved for all values of n but it is solved for 10^18 or larger. In the problem the range of 2n fits into this range. So for n=1 the output is No else the output is Yes.

### AUTHOR’S SOLUTIONS:

Author’s solution can be found here.

Modified the question to ’ & find the prime numbers ’ Then the solution is:-

void main()
{
clrscr();
int n;
cin>>n;
int prime;
prime=2;
prime=3;
prime=5;
prime=7;
int flag=0;
int c=4;

``````for(int i=8;i<2*n;i++)
{
if((2*n)%i!=0  && i%5!=0 && i%2!=0 && i%7!=0 && i%3!=0)
{

prime[c++]=i;

}
}
c--;
for(i=0; i<c;i++)
{
for(int j=0;j<c;j++)
{
if(prime[i]+prime[j]==2*n)
cout<<" --> "<<prime[i]<< " + "<< prime[j]<<endl;
}
}
getch();
}
``````

PS: I have no clue what Code Chef is Displaying I copied the code fine!