Thread: prime ring

hi i am newbie here, i am not trying to ask for the answer here...
i am just asking for opinion

can someone let me know what should i include in this type of question please.

http://acm.uva.es/p/v5/524.html

please visit this website for understanding http://acm.uva.es/p/v5/524.html

thank you

please make it simple as i am the newbie of C++..

> can someone let me know what should i include in this type of question please.
Blackroot has already given you an answer - a function to check whether a given number is prime or not is a good start.

I suppose other functions would be to
- check a whole ring for being prime, as discussed in the assignment
- generate all possible rings according to some input
- get and validate some input from the user.

Originally Posted by Blackroot

BOOL IsPrime(int n) {
int i;
BOOL prime;

cout << "Enter number to prime-test";
cin >> n;

for(i = 2; i <= sqrt((double) n); i++)
if(n % 1 == 0)
is_prime = false;
}
[/code]

This code is wrong! You should not divide by 1 -> (n%1)!!!!
here u have more efficient one

Code:

BOOL IsPrime(int n) {
  
if (n<=2)
return true;

if (n%2 == 0)
return false;

 for(i = 3; i <= sqrt((double) n); i+=2){
  if(n % i == 0){
   return false;
  }
}
return true;
}

u can check a number if it is prime by calling function with a argument that could by any number within int range!

i am sorry guyz.. i still dont understand ...

well can someone give example, such as i
INPUT: 4
and the OUTPUT which i done it by myself (1,2,3,4 and 1,4,3,2)
correct me if i am wrong..
can someone guide me to the process please.

can some one tell me how can i modify this code so that i can ask the user input from 1-16....

Code:

int ring[16];
int m;

int main()
{
    int  i, j, k;
//  insert the 1 value into first position which is ring[0]
    ring[0] = 1;
    
    while (scanf("%d", &m))
    {
        if (m == 0)
        break;

//  printf("Get %d\n", m);
        if (FindNumber(1) == true)
        {
            for(j=0; j<m; j++)
            {
                printf("%d ", ring[j]);
            }
            printf("\n");
        }
    }// end while.
    system("pause");
    return 0;
}