You'd simply have to keep track of : has particular alphabet already been
used or not. You can do this by maintaining a 'used' array of 0/1 . Set and
unset the respective index before and after the recursion.
Here's the modified code:
#include<stdio.h>
#include<string.h>
#include<malloc.h>
*void allLexicographicRecur (char *str, char* data, int *used, int last,
int index)*
{
int i, len = strlen(str);
// One by one fix all characters at the given index and recur for the
// subsequent indexes
for ( i=0; i<len; i++ )
{
// Fix the ith character at index and if this is not the last index
// then recursively call for higher indexes
* if(used[i] == 0){*
data[index] = str[i] ;
* used[i] = 1;*
// If this is the last index then print the string stored in data[]
if (index == last)
printf("%s\n", data);
else // Recur for higher indexes
allLexicographicRecur (str, data, used, last, index+1);
* used[i] = 0;*
* }*
}
}
/* This function sorts input string, allocate memory for data (needed for
allLexicographicRecur()) and calls allLexicographicRecur() for printing
all
permutations */
// Needed for library function qsort()
int compare (const void * a, const void * b)
{
return ( *(char *)a - *(char *)b );
}
void allLexicographic(char *str)
{
int len = strlen (str) ;
// Create a temp array that will be used by allLexicographicRecur()
char *data = (char *) malloc (sizeof(char) * (len + 1)) ;
data[len] = '\0';
// Sort the input string so that we get all output strings in
// lexicographically sorted order
qsort(str, len, sizeof(char), compare);
// Now print all permutaions
* int used[len], i;*
* for(i=0; i<len; ++i)*
* used[i] = 0;*
*
*
* allLexicographicRecur (str, data, used, len-1, 0);*
// Free data to avoid memory leak
free(data);
}
// Driver program to test above functions
int main()
{
char str[] = "ABC";
printf("All permutations with repetition of %s are: \n", str);
allLexicographic(str);
getchar();
return 0;
}
On 30 October 2012 22:00, Nishant Pandey <[email protected]>wrote:
> void allLexicographicRecur (char *str, char* data, int last, int index)
> {
> int i, len = strlen(str);
>
> // One by one fix all characters at the given index and recur for the
> // subsequent indexes
> for ( i=0; i<len; i++ )
> {
> // Fix the ith character at index and if this is not the last
> index
> // then recursively call for higher indexes
> data[index] = str[i] ;
>
> // If this is the last index then print the string stored in
> data[]
> if (index == last)
> printf("%s\n", data);
> else // Recur for higher indexes
> allLexicographicRecur (str, data, last, index+1);
> }
> }
>
> /* This function sorts input string, allocate memory for data (needed for
> allLexicographicRecur()) and calls allLexicographicRecur() for printing
> all
> permutations */
> void allLexicographic(char *str)
> {
> int len = strlen (str) ;
>
> // Create a temp array that will be used by allLexicographicRecur()
> char *data = (char *) malloc (sizeof(char) * (len + 1)) ;
> data[len] = '\0';
>
> // Sort the input string so that we get all output strings in
> // lexicographically sorted order
> qsort(str, len, sizeof(char), compare);
>
> // Now print all permutaions
> allLexicographicRecur (str, data, len-1, 0);
>
> // Free data to avoid memory leak
> free(data);
> }
>
> // Needed for library function qsort()
> int compare (const void * a, const void * b)
> {
> return ( *(char *)a - *(char *)b );
> }
>
> // Driver program to test above functions
> int main()
> {
> char str[] = "ABC";
> printf("All permutations with repetition of %s are: \n", str);
> allLexicographic(str);
> getchar();
> return 0;
> }
>
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