[C/Cpp] an example of permutation

// Permutation,  total number of cases = R^N

#include <stdio.h>

#define N 3
#define R 4 

int temp[R];  
FILE *fp ;


void permutation(int value)
{
  int i;
  
  if(R==value){ 
    for(i=0; i<R; i++){
      printf("%d ", temp[i]);
      fprintf(fp, "%d ", temp[i]);
    }
    printf("\n"); 
    fprintf(fp, "\n");
    return;
  }
  for(i=1; i<=N; i++){
    temp[value]=i;
    permutation(value+1);
  }
}


int main()
{
    fp = fopen("all_cases.txt", "w");
    permutation(0);  
    return 0;
    fclose(fp);
}