PROJECT EULER SOLUTION # 7

Solution to problem number 7 of Project Euler.

Question # 7

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.

What is the 10 001st prime number?

Solution # 7

/*********************************************************************************************************/

#include<stdio.h>

#include<conio.h>

#include<stdlib.h>

#include<math.h>

#include<time.h>

long i_th_prime(int);

int main()

{

                int i=10001;

                printf("%ld",i_th_prime(i));

                printf("\nEXECUTION TIME = %f\n",(clock()/(float)CLK_TCK));

                system("pause");

}

long i_th_prime(int num)

{

                long i;

                int counter=0;

                for(i=2;;i++)

                {

                                if(isprime(i))

                                                counter++;

                                if(counter==num)

                                                break;

                }

                return i;

}

int isprime(long num)

{

                long i;

                for(i=2;i<=sqrt(num);i++)

                {

                                if(num%i==0)

                                                return 0;

                }

                return 1;

}

/**********************************************************************************************************/