Borne Games Forum

1. 

   Coolnesiac
   Member

   Post Count: 1067
   

   #include <iostream>

   //version 8.65)

   using namespace std;

   int mul5 = 0;
   int mul3 = 0;
   int numTo = 1000;

   int main (int argc, char * const argv[]) {
   for (int i = 0; i < numTo; i += 5) {
   mul5 += i;
   cout << "\n" << ((i/5)+1) << ":" << mul5 << " (" << i << " ";
   }
   cout << "\n[:" << mul5 << "]";
   //WJUK, I just calculated the sum of multiples of 5...
   return 0;
   }

   Coolnesiac Fan Club Members: Coolnesiac, profzeppelin
   http://davidlougheed.com/reverse.php

   Posted 2 years ago #
   Private
2. 

   WJUK
   The Lone Ranger

   Post Count: 14104
   

   Right, you're slightly confused. You were closer the first time.

   The question asks for the sum of multiples of 3 or 5 up to 1000.

   Now, let's just look at some of the multiples first.

   Here are the multiples of 3 under 100: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99.

   Now the multiples of 5 under 100: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95.

   Do you notice... some overlap?

   
   Don't click here

   Posted 2 years ago #
3. 

   Coolnesiac
   Member

   Post Count: 1067
   

   oh... numbers that are both multiples of 3 AND 5? hm.

   Coolnesiac Fan Club Members: Coolnesiac, profzeppelin
   http://davidlougheed.com/reverse.php

   Posted 2 years ago #
   Admin
4. 

   WJUK
   The Lone Ranger

   Post Count: 14104
   

   Bingo!

   Now, there's a multitude of ways to program in what you need. And for now, there's not that much time in compute-time, since you're not doing that many computations.

   
   Don't click here

   Posted 2 years ago #
5. 

   Coolnesiac
   Member

   Post Count: 1067
   

   Still doesn't work. My current result is 33165. Sorry for being helpless, but learning C++ from 1992 textbooks is hard

   Code:

   #include <iostream>

   //version 10.1)

   using namespace std;

   int res = 0;

   int fivez[200];
   int treez[333];

   int main (int argc, char * const argv[]) {
   cout << "\nGenerating Multiples of Five...\n";
   for(int a = 0; a < 1000; a+=5) {
   fivez[a/5] = a;
   cout << a;
   }
   cout << "\nGenerating Multiples of Three...\n";
   for(int b = 0; b < 1000; b+=3) {
   treez[b/3] = b;
   cout << b;
   }
   cout << "\nFinding Matches...\n";
   cout << "0";
   for(int m1 = 0; m1 < 200; m1++) {
   for (int m2 = 0; m2 < 333; m2++) {
   if (fivez[m1] == treez[m2]) {
   res += fivez[m1];
   cout << "+" << fivez[m1];
   }
   }
   }
   cout << "\n\nResult: " << res << "\n\n";

   return 0;
}


   Coolnesiac Fan Club Members: Coolnesiac, profzeppelin
   http://davidlougheed.com/reverse.php

   Posted 2 years ago #
6. 

   Nyubis
   Nyubis of Strata

   Post Count: 9151
   

   ...I think you're both wrong.

   In the example they clearly take all the multiples of 3 below 10 [3, 6, 9] an the multiples of 5 below 10 [5]. What you need to do is 3 + 5 + 6 + 9, which is 23. That's how the example is done.
   You don't need to take the numbers that are both multiples of 3 and 5, because the lowest of that would be 15, and that's higher than 10 so they couldn't have done the example.

   Not in cruelty
   Not in wrath
   the Reaper came today.

   An Angel visited
   this gray path
   And took the cube away.

   Posted 2 years ago #
7. 

   Coolnesiac
   Member

   Post Count: 1067
   

   I did that and got the wrong answer. LOLZ.

   Coolnesiac Fan Club Members: Coolnesiac, profzeppelin
   http://davidlougheed.com/reverse.php

   Posted 2 years ago #
8. 

   Nyubis
   Nyubis of Strata

   Post Count: 9151
   

   Is that what you posted at the top of the page? Because there you only calculate the multiples of 5.

   Not in cruelty
   Not in wrath
   the Reaper came today.

   An Angel visited
   this gray path
   And took the cube away.

   Posted 2 years ago #
9. 

   Coolnesiac
   Member

   Post Count: 1067
   

   No, this is the current code. But it gets multiples of 3 and 5. I solved No 7, anyway.

   Still doesn't work. My current result is 33165. Sorry for being helpless, but learning C++ from 1992 textbooks is hard
   Code:

   #include <iostream>
//version 10.1)
using namespace std;
int res = 0;
int fivez[200];<>
int treez[333];
int main (int argc, char * const argv[]) {<>
cout << "\nGenerating Multiples of Five...\n";<>
for(int a = 0; a < 1000; a+=5) {<>
fivez[a/5] = a;<>
cout << a;<>
}<>
cout << "\nGenerating Multiples of Three...\n";<>
for(int b = 0; b < 1000; b+=3) {<>
treez[b/3] = b;<>
cout << b;<>
}<>
cout << "\nFinding Matches...\n";<>
cout << "0";<>
for(int m1 = 0; m1 < 200; m1++) {<>
for (int m2 = 0; m2 < 333; m2++) {<>
if (fivez[m1] == treez[m2]) {<>
res += fivez[m1];<>
cout << "+" << fivez[m1];<>
}<>
}<>
}<>
cout << "\n\nResult: " << res << "\n\n";
return 0;<>
}<>


   Coolnesiac Fan Club Members: Coolnesiac, profzeppelin
   http://davidlougheed.com/reverse.php

   Posted 2 years ago #
10. 

    WJUK
    The Lone Ranger

    Post Count: 14104
    

    @Nyubis: That's what I was trying to get at without giving the answer away completely.

    Looking back on my code for this (from January 15th 2010!), I have this:

    sum = 0

    for i in range(1000):
    if (i % 3) == 0:
    sum += i
    elif (i % 5) == 0:
    sum += i

    print sum

    Which is certainly one way to do it. Although, technically, a faster way to do it would be Cool's way.
    >Generate and sum up all multiples of 3.
    >Do the same for 5. Add these up.
    >Then generate and sum up all multiples of 15. BUT remove this from the total of multiples of 3 & 5.

    Technically, this should be faster, although with computer speeds now the time difference will be negligible.

    
    Don't click here

    Posted 2 years ago #
11. 

    Coolnesiac
    Member

    Post Count: 1067
    

    Thanks. all I had been doing wrong was adding it to sum twice if it was a multiple of 3 and 5.

    Coolnesiac Fan Club Members: Coolnesiac, profzeppelin
    http://davidlougheed.com/reverse.php

    Posted 2 years ago #
12. 

    WJUK
    The Lone Ranger

    Post Count: 14104
    

    S'alright, sometimes it helps to just stand back from the problem and work it out on paper first. Trust me, it works.

    
    Don't click here

    Posted 2 years ago #
13. 

    Nyubis
    Nyubis of Strata

    Post Count: 9151
    

    @WJUK: Could you help me on problem 10? I have the array containing all primes below 2mil, but when I do sum(array) it gives me a number with an L attached to the end. I tried submitting the number but apparently that's wrong, even though I'm fairly sure I did everything right. After some googling it seems that the L means that I should use a long instead of an integer, but whenever I convert it to long or do long(sum(array)) it still gives me the same result.

    Not in cruelty
    Not in wrath
    the Reaper came today.

    An Angel visited
    this gray path
    And took the cube away.

    Posted 2 years ago #
14. 

    WJUK
    The Lone Ranger

    Post Count: 14104
    

    Don't worry about the L at the end. It just shows that the variable is now classified as a "long" and doesn't actually affect it.

    What's the number you get?
    Showing me your code might help me in pinpointing what you may have potentially gotten wrong.

    
    Don't click here

    Posted 2 years ago #
15. 

    Nyubis
    Nyubis of Strata

    Post Count: 9151
    

    So the number was wrong? That sucks, I was pretty sure I did everything right.

    Since the forum can't view the quite important indents,
    pastebin.

    Not in cruelty
    Not in wrath
    the Reaper came today.

    An Angel visited
    this gray path
    And took the cube away.

    Posted 2 years ago #
16. 

    WJUK
    The Lone Ranger

    Post Count: 14104
    

    Haha, your code is completely right. There's nothing wrong with it.

    You're just missing one crucial detail.

    for i in range(1, max, 2):

    This makes i = 1, 3, 5, 7... etc. (well, actually it just iterates through a list, but that's not the point here)

    But I recall there was one special prime... hm...

    Does that ring a bell or do you want me to elaborate further?

    
    Don't click here

    Posted 2 years ago #
17. 

    Nyubis
    Nyubis of Strata

    Post Count: 9151
    

    ...Oh bloody hell.
    I am an idiot.
    Really.
    Why didn't I see this myself...

    Anyway, thanks.

    Not in cruelty
    Not in wrath
    the Reaper came today.

    An Angel visited
    this gray path
    And took the cube away.

    Posted 2 years ago #
18. 

    WJUK
    The Lone Ranger

    Post Count: 14104
    

    No problem.

    You should definitely have the right answer now (your answer was literally lacking that number XD ).

    
    Don't click here

    Posted 2 years ago #
19. 

    Nyubis
    Nyubis of Strata

    Post Count: 9151
    

    Yes, it's right now. I still can't believe my stupidity.

    Not in cruelty
    Not in wrath
    the Reaper came today.

    An Angel visited
    this gray path
    And took the cube away.

    Posted 2 years ago #
20. 

    WJUK
    The Lone Ranger

    Post Count: 14104
    

    Haha don't worry. It's always the little things like typos etc.

    
    Don't click here

    Posted 2 years ago #

RSS feed for this topic

Reply

You must log in to post.