Nossa4ever
asked on
recursive permutation method
i try to solve this method but i couldn't reach to anything . this is the Question :
You have an index card with the letter C written on one side, and S on the other. You want to see ALL of the possible ways the card will land if you drop it n times. Write a recursive method that prints each session of dropping the cards with C's and S's. For example of you drop it 4 times in a given session, all possible ways to drop it are as follows:
CCCC
CCCS
CCSC
CCSS
CSCC
CSCS
CSSC
CSSS
SCCC
SCCS
SCSC
SCSS
SSCC
SSCS
SSSC
SSSS
*Note: The possible ways would have to print in this specific order.
AND this is my solve but it's wrong :
static void permute(int n)
{
int j;
char a []={'C','S'};
int i = n ;
if (i == 0)
System.out.println("Nothin
else
{
for (j = i; j <= n; j++)
{
System.out.println(a);
permute(n-1);
String u = a[j] * a[j];
}
}
}
You have an index card with the letter C written on one side, and S on the other. You want to see ALL of the possible ways the card will land if you drop it n times. Write a recursive method that prints each session of dropping the cards with C's and S's. For example of you drop it 4 times in a given session, all possible ways to drop it are as follows:
CCCC
CCCS
CCSC
CCSS
CSCC
CSCS
CSSC
CSSS
SCCC
SCCS
SCSC
SCSS
SSCC
SSCS
SSSC
SSSS
*Note: The possible ways would have to print in this specific order.
AND this is my solve but it's wrong :
static void permute(int n)
{
int j;
char a []={'C','S'};
int i = n ;
if (i == 0)
System.out.println("Nothin
else
{
for (j = i; j <= n; j++)
{
System.out.println(a);
permute(n-1);
String u = a[j] * a[j];
}
}
}
krakatoa
Somehow, recursion or not, I believe you'd need to keep track of the perms. you'd previously created.
ASKER CERTIFIED SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
Let permute(1) return a list of the Strings "C" and "S"
Then you can write permute(n) as
* Take the result of permute(n-1)
* for each String element in the result of permute(n-1)
prefix it with "C" and add it to your result list
for each String element in the result of permute(n-1)
prefix it with "S" and add it to your result list
return your result list
Now you can get your desired output by writing:
for (String each : permute(4)) {
System.out.println(each);
}
Then you can write permute(n) as
* Take the result of permute(n-1)
* for each String element in the result of permute(n-1)
prefix it with "C" and add it to your result list
for each String element in the result of permute(n-1)
prefix it with "S" and add it to your result list
return your result list
Now you can get your desired output by writing:
for (String each : permute(4)) {
System.out.println(each);
}
@Valeri: don't post ready-out-of-the-box code for homework questions!
@zzynx:
I agree! Probably you are right and this is homework...?! I don't know...?!
Anyway, understanding recursion, if the author of the question is student, is difficult... that's way I thing that "ready" code will be useful for him and will help him to solve next recursion tasks by himself...
I agree! Probably you are right and this is homework...?! I don't know...?!
Anyway, understanding recursion, if the author of the question is student, is difficult... that's way I thing that "ready" code will be useful for him and will help him to solve next recursion tasks by himself...
Probably you are right and this is homework...?! I don't know...?!I think there's no doubt at all that this is a homework/school question.
... understanding recursion (...) is difficultDifficulty is never a good alibi for posting full blown code in the case of a homework question.