## Friday, June 11, 2010

### Project Euler Problem 7 in C

ProjectEuler once more! In my opinion, it's logical to do this problem before Problem 3 as Problem 3 requires prime numbers too. Also, Problem 3 has the issue of it being an awkward problem due to the high number... Anyways, here's the Problem:
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6^(th) prime is 13.

What is the 10001^(st) prime number?

And here's my code:

`#include <stdio.h>#include <math.h>int isPrime(int test){    int calculateTo = (int) sqrt(test);    for(int i=3; i<=calculateTo; i+=2)    {        if(test%i==0)            return 0;    }    return 1;}int main(){    int howHigh=10001;    int counter=1;    while (1)    {        for(int i=3; ; i+=2)        {            if( isPrime(i) )                counter++;            if(counter==howHigh)            {                printf("%d\n", i);                return 0;            }        }    }    return 1;}`

Execution Time: 0.187 s

Not too shabby in my opinion! So that's just about it.
NotMyFault