Question

Write a program to print in such a pattern given above. Please tell me how to write this program.

Answer 1

Here is a solution that is used as a basis in backtracking.

NewPermutation

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// C program to print all permutations with duplicates allowed  

#include <stdio.h>  

#include <string.h>  

 

/* Function to swap values at two pointers */

void swap(char *x, char *y)  

{  

   char temp;  

   temp = *x;  

   *x = *y;  

   *y = temp;  

}  

 

/* Function to print permutations of string  

  This function takes three parameters:  

  1. String  

  2. Starting index of the string  

  3. Ending index of the string. */

void permute(char *a, int l, int r)  

{  

  int i;  

  if (l == r)  

    printf("%s\n", a);  

  else

  {  

      for (i = l; i <= r; i++)  

      {  

         swap((a+l), (a+i));  

         permute(a, l+1, r);  

         swap((a+l), (a+i)); //backtrack  

      }  

  }  

}  

 

/* Driver program to test above functions */

int main()  

{  

   char str[] = "ABC";  

   int n = strlen(str);  

   permute(str, 0, n-1);  

   return 0;