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Re: Project Euler - add all natural numbers below 1000

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On 05/23/2012 01:03 PM, arnuld wrote:
> AIM: To write a program to add all natural numbers below 1000 that are
> multiples of 3 or 5.
>
> WHAT I GOT:  it works

Does it? How did you test it?

Let's test it with a limit of 16 instead of 1000. What is the correct 
answer? I suspect you want it to be

   3 + 5 + 6 + 9 + 10 + 12 + 15 = 60

but the output of your program is 75 because it will add 15 twice (it is 
a multiple of both 3 and 5).


>
> Question-1:  Look at the for loop, instead of looping for 1000 times and
> checking the value inside, I am simply looping it 1000/3 = 333 times. Ist
> that impressive ?
>
> Question-2: Can it be improved ?

Yes, programs that don't work can always be improved.

>
>
>
> /* Add all the natural numbers below one thousand that are multiples of 3
> or 5. */
>
> #include<stdio.h>
> #include<stdlib.h>
>
> int main(void)
> {
>    const int limit = 7;

I suspect you mean limit = 1000;

>    const int multiple_A = 3;
>    const int multiple_B = 5;
>    unsigned long sum;
>    int i, j;
>    sum = 0;
>
>    for(i = 0, j = 0; (i<= limit); i = i + multiple_A, j = j + multiple_B)
>      {
>        printf("i = %d, j = %d\n", i, j);
>        if(j<= limit)
> 	{
> 	  sum = sum + i + j;
> 	}
>        else
> 	{
> 	  sum = sum + i;
> 	}
>      }
>
>    printf("Sum = %lu\n", sum);
>
>    return 0;
> }
>

regards,
Sander

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Project Euler - add all natural numbers below 1000 arnuld <sunrise@invalid.address> - 2012-05-23 11:03 +0000
  Re: Project Euler - add all natural numbers below 1000 Bjoern Hoehrmann <bjoern@hoehrmann.de> - 2012-05-23 13:30 +0200
  Re: Project Euler - add all natural numbers below 1000 "H.J. Sander Bruggink" <sander.bruggink@uni-due.de> - 2012-05-23 14:11 +0200
    Re: Project Euler - add all natural numbers below 1000 arnuld <sunrise@invalid.address> - 2012-05-23 12:44 +0000
      Re: Project Euler - add all natural numbers below 1000 Ike Naar <ike@sverige.freeshell.org> - 2012-05-23 13:55 +0000
      Re: Project Euler - add all natural numbers below 1000 bob <bob@coolfone.comze.com> - 2012-05-23 06:56 -0700
  Re: Project Euler - add all natural numbers below 1000 jt@toerring.de (Jens Thoms Toerring) - 2012-05-25 09:29 +0000
    Re: Project Euler - add all natural numbers below 1000 bob <bob@coolfone.comze.com> - 2012-05-25 06:26 -0700
      Re: Project Euler - add all natural numbers below 1000 jt@toerring.de (Jens Thoms Toerring) - 2012-05-26 21:52 +0000
  Re: Project Euler - add all natural numbers below 1000 "BartC" <bc@freeuk.com> - 2012-05-27 01:52 +0100

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