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Computer Science Level 2

Find the 2014th prime number.

Example: The 2nd prime number is 3 and the 3rd prime number is 5.


The answer is 17497.

Charlton Teo by Charlton Teo , 21, Singapore

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2 solutions

Ronak Agarwal
Sep 5, 2014

Java code : 

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int sum = 0 ;
    int i = 2 ;
    for(;;){
    if(isprime(i))
        sum=sum+1 ;
    if(sum==2014)
        break ;
    i=i+1 ;

    }
    System.out.print(i) ;

For checking whether a number is prime I have created a method isprime whose code is as follows. 

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public static boolean isprime(long n){
   if(n==2)
       return true ;
   else
   {int k = (int) Math.pow(n,0.5) ;
   if(n%2==0)
       return false ;
   else
   {for(int s=3;s<k+1;s=s+2){
   if(n%s==0)
       return false ;}
   return true ;}

   }

3 Helpful 0 Interesting 0 Brilliant 0 Confused 

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


int main() {
 int a,b,x,y,i,j;
    cin>>x;
    cin>>y;
    a=0;
    for(i=2;i<x;i++)

    {  b=0;
        for(j=2;j<i;j++)
     {      if(i%j!=0)
              b++ ;
     }
         if(b==i-2)
         a++;
             if(a==y)
             break;
    }
     cout<<i;
    return 0;
}

Where y = 2014 y=2014 and x x is a sufficiently large number(in this case, x > 20000 x>20000 .

Siddharth G - 6 years, 8 months ago
Bill Bell
Dec 5, 2014

I should be ashamed. Using the Python sympy library.

I have already written prime number code several times though.

1 Helpful 0 Interesting 0 Brilliant 0 Confused

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