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Join Date: Nov 2004
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Newbie Poster
Having trouble where to go next on this program:
1. If n is even, then you may give back exactly n/2 bears.
2. If n is divisible by 3 or 4, then you may multiply the last two digits of n and give back this many bears. By the way, the last digit of n is n%10, and the next-to-last digit is ((n%100)/10. Keep in mind that the result of these operations may be 0, in which case, you don't want to use this option.
3. If n is divisible by 5, then you may give back exactly 42 bears.
Here is what I have so far:
<< moderator edit: added code tags:
Here is how a sample should look like:
bears.
The goal of the game is to end up with EXACTLY 42 bears.
For example, suppose that you start with 250 bears. Then you could make these moves:
• --Start with 250 bears.
• --Since 250 is divisible by 5, you may return 42 of the bears, leaving you with 208 bears.
• --Since 208 is even, you may return half of the bears, leaving you with 104 bears.
• --Since 104 is even, you may return half of the bears, leaving you with 52 bears.
• --Since 52 is divisible by 4, you may multiply the last two digits (resulting in 10) and return these 10 bears. This leaves you with 42 bears.
• --You have reached the goal!
I am having trouble trying to backtrack when n becomes less than 42 in the if statements. ANy help would be much appreciated.
1. If n is even, then you may give back exactly n/2 bears.
2. If n is divisible by 3 or 4, then you may multiply the last two digits of n and give back this many bears. By the way, the last digit of n is n%10, and the next-to-last digit is ((n%100)/10. Keep in mind that the result of these operations may be 0, in which case, you don't want to use this option.
3. If n is divisible by 5, then you may give back exactly 42 bears.
Here is what I have so far:
bool count(int x)
{
if(x==42){
return true;
}else if (x<42){
return false;
}else{
if(x%5==0){
return count(x-42);
}else if(x%2==0){
return count(x/2);
}else if(x%3==0 || x%4==0){
return count(x - ((x%10) * ((x%100)/10))));
}
}
int main()
{
count(250);
return 0;
}[code][/code] >>Here is how a sample should look like:
bears.
The goal of the game is to end up with EXACTLY 42 bears.
For example, suppose that you start with 250 bears. Then you could make these moves:
• --Start with 250 bears.
• --Since 250 is divisible by 5, you may return 42 of the bears, leaving you with 208 bears.
• --Since 208 is even, you may return half of the bears, leaving you with 104 bears.
• --Since 104 is even, you may return half of the bears, leaving you with 52 bears.
• --Since 52 is divisible by 4, you may multiply the last two digits (resulting in 10) and return these 10 bears. This leaves you with 42 bears.
• --You have reached the goal!
I am having trouble trying to backtrack when n becomes less than 42 in the if statements. ANy help would be much appreciated.
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Join Date: Sep 2004
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Why are you using recursion for this? A loop would be trivial.
I'm a programmer. My attitude starts with arrogance, holds steady at condescension, and ends with hostility. Get used to it.
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Newbie Poster
THe problem requires you to solve it recursively. I ended up solving the problem. Here is the code:
bool count(int x)
{
if(x==42)
return true;
if (x<42)
return false;
if(x%3==0 || x%4==0)
{ /* rule 2, some cases eliminates rule 1 and rule 3 */
int a = (x%10 * ((x%100)/10));
if(a!=0)
return count(x-a);
/* if the last two digits give 0 we don't want to use that
* So what should we do ??
* The scenario for this is:
* a) 0x
* - gets caught by rule 1, 50% of the time and rule 3, 10% of the time
* b) x0
* - gets caught by rule 3 100% of the time
*/
}
if(x%5==0) /* rule 3 and in some cases eliminates rule 1 */
return count(x-42);
if(x%2==0) /* rule 1 */
return count(x/2);
/* what should we do if nothing matches (like 59) ??
* Since we got no rule to catch that, we better return false
*/
return false;
} •
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Join Date: Sep 2004
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>THe problem requires you to solve it recursively.
Naturally. I wonder when teachers will start giving good assignments for learning recursion instead of contriving silly stuff that could more easily be solved with a loop. :rolleyes:
Naturally. I wonder when teachers will start giving good assignments for learning recursion instead of contriving silly stuff that could more easily be solved with a loop. :rolleyes:
I'm a programmer. My attitude starts with arrogance, holds steady at condescension, and ends with hostility. Get used to it.
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Join Date: Dec 2006
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Newbie Poster
I've been thinking/saying that for a long time... It's actually why I struggle at times... because I can do the problem, but it's hard to "dumb down" myself to do the problem the way they want it.
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Join Date: Dec 2006
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Newbie Poster
Actually doesn't work all the time... try inputting 168
If you have 168, is' even, divide it in 1/2 you can return n/2 bears
168/2 = 84
84 is even so divide it by 2 and walla... 42
Your code is saying it's false. just an FYI
If you have 168, is' even, divide it in 1/2 you can return n/2 bears
168/2 = 84
84 is even so divide it by 2 and walla... 42
Your code is saying it's false. just an FYI
Last edited by DeadDrunk : Dec 13th, 2006 at 10:21 pm.
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