is this a permutation question or combination question, the example does not
give a hint that way...
the idea is to ensure that starting at position n, successively allow all
possible non-used character in position n, and then possible combinations
starting from position n+1 ensuring that the strin length to be printed is r
int length=strlen(pIn);
void permute(char *pOut, int Outindex,bool used[], int included)
{
if (included==r) printOutPutArray(pOut); return;
}
for (int i=0;i<length;i++)
{
if used[i] continue;
out[outIndex++] = a[i];
used[i]=true;
permute(out, used, included+1);
used[i]=false;
outIndex--;
}
Best Regards
Ashish Goel
"Think positive and find fuel in failure"
+919985813081
+919966006652
On Thu, Jul 15, 2010 at 5:57 AM, Gene <gene.ress...@gmail.com> wrote:
> On Jul 14, 8:53 am, ankit mahendru <ankit.mahend...@gmail.com> wrote:
> > Write the code to print combinations of a given array (n& r were given)
> e.g
> > for abcde .r=3 ...print " abc", "bcd' "cde" etc
>
> The problem has a nice recursive structure. To choose r items from a
> set of items numbered m..n, make a decision to choose one of these.
> Say it's i, where m <= i <= n. Then recur to find the rest of the
> (r-1) items from the subset i+1...n. The base case is r==0, which
> means you have found all the items you need and can print the result.
> (You can refine this a bit to get rid of some useless recursive calls.
> How?)
>
> Here is one approach of many possible to code this idea:
>
> #include <stdio.h>
> #include <string.h>
>
> typedef struct choice_s {
> struct choice_s *prev;
> int i;
> } CHOICE;
>
> void print_choices(char *set, CHOICE *choices)
> {
> if (choices) {
> print_choices(set, choices->prev);
> putchar(set[choices->i]);
> }
> }
>
> void print_combinations(char *set, int n, int r, CHOICE *choices)
> {
> if (r == 0) {
> print_choices(set, choices);
> putchar('\n');
> }
> else {
> CHOICE choice[1] = {{ choices }};
> for (choice->i = choices ? choices->i + 1 : 0; choice->i < n;
> choice->i++)
> print_combinations(set, n, r - 1, choice);
> }
> }
>
> int main(int argc, char *argv[])
> {
> int r;
> char *s;
>
> if (argc == 3 && sscanf(argv[2], "%d", &r) == 1 && strlen(argv[1])
> >= r)
> s = argv[1];
> else {
> s = "abcde";
> r = 3;
> }
> print_combinations(s, strlen(s), r, 0);
> return 0;
> }
>
> $ ./a.out
> abc
> abd
> abe
> acd
> ace
> ade
> bcd
> bce
> bde
> $
>
> --
> You received this message because you are subscribed to the Google Groups
> "Algorithm Geeks" group.
> To post to this group, send email to algoge...@googlegroups.com.
> To unsubscribe from this group, send email to
> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com>
> .
> For more options, visit this group at
> http://groups.google.com/group/algogeeks?hl=en.
>
>
--
You received this message because you are subscribed to the Google Groups
"Algorithm Geeks" group.
To post to this group, send email to algoge...@googlegroups.com.
To unsubscribe from this group, send email to
algogeeks+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/algogeeks?hl=en.
