Dfyjkt

I have this code for permutation WITH repetition. Would anyone help to modify it to be WITHOUT repetition. I can't figure it out.

int array1 = 1, 2, 3; //array can be 1,1,2,3 for example also
int array2[3];

void permWithRep (int array1, int array2, int last, int index)
int i, len = last+1;

 enter code here
 for ( i=0; i<len; i++ )
 
 array2[index] = array1[i] ;

 if (index == last)
 for(int i = 0; i < 3; i++) 
 printf("%d ", array2[i]);
 
 printf("n");
 
 else // Recur for higher indexes
 permWithRep (array1, array2, last, index+1);
 


int main()

 int len = sizeof(array1)/sizeof(int);
 permWithRep (array1, array2, len-1, 0);
 return 0;

I tested this on few inputs and it works.

There is certainly a better way to do it, but that's what i did:

#include <stdio.h> 

int array1 = 1, 2, 3; //array can be 1,1,2,3 for example also
int array2[3]; 
int fixed[3];



void permWithRep(int array1, int array2,int fixed_index, int size , int level)

 if(level == size) return print_array(array2,size);

 for(int k = 0; k< size; k++)

 if(!is_present_in_fixed(fixed_index,level,k))
 fixed_index[level] = k;
 array2[level] = array1[k];
 permWithRep(array1,array2,fixed_index,size,level+1);
 

 


void print_array(int array, int size)
 for(int k = 0; k < size; k++)printf("%d ",array[k]);
 printf("n");


int is_present_in_fixed(int array, int size, int element )
 for(int k =0; k<size;k++)
 if(element == array[k]) return 1;
 return 0;




int main()

 int len = sizeof(array1)/sizeof(int);
 permWithRep (array1, array2, fixed, len, 0);
 return 0;

What I did:

• Add an array (fixed_index) that keep track of the already visited indexes for one permutation.


• In the loop, check if the index of current element belongs to the index already visited in that permutation (is_present_in_fixed(fixed_index,level,k)).


• If so, it just skip that element (it does not enter the if statement).


• Otherwise adds that element to the visited for that permutation and go on with recursive call.


• When all array has been iterated on (level == size), just print the results contained in array2.