PROJECT EULER SOLUTION # 28

Solution to problem number 28 of Project Euler.

Question # 28

Starting with the number 1 and moving to the right in a clockwise direction a 5 by 5 spiral is formed as follows:

21 22 23 24 25
20  7  8  9 10
19  6  1  2 11
18  5  4  3 12
17 16 15 14 13

It can be verified that the sum of the numbers on the diagonals is 101.

What is the sum of the numbers on the diagonals in a 1001 by 1001 spiral formed in the same way?

Solution # 28

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

#include<stdio.h>

#include<conio.h>

#include<math.h>

#include<stdlib.h>

#include<time.h>

long fun(int);

int main()

{

       int i;

       long sum=1;

       for(i=1;i<=500;i++)

              sum+=fun(i);

      

       printf("Answer = %ld\n",sum);

 

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

       system("pause");

}

long fun(int n)

{

       long sum1=0,sum2=0,sum3=0,sum4=0;

       int temp;

       temp=2*n+1;

       sum1=pow((double)temp,2);

       sum2=pow((double)temp-2,2)+temp-1;

       sum3=sum2+2*n;

       sum4=sum3+2*n;

       return (sum1+sum2+sum3+sum4);

}

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