#include<stdio.h>
/*List all permutations of n characters */
/* CopyLeft by tsaiwn@csie.nctu.edu.tw */
/*  輸入 n 個不同字母然後印出該些字母的所有排列 */
int val[99], id=-1, nPerm, n;  /* n characters */
int getLetters();
void visit(), writePerm();
char letters[99];
int main( ) {
   while(38) {
      n = getLetters();
      if(n <= 0) break;
      printf("n=%d\n", n);
      id = -1; nPerm=0;
      visit(0);
      printf("===Total %d permutations.\n", nPerm);
   } printf("\nBye!\n");
}
void visit(int k) {
   int t;
   val[k] = ++id;
   /* printf(" id=%d ", id);  /**/
   if(id==n-1) writePerm();
   for(t=0; t< n; ++t)
      if(val[t] == 0) visit(t);
   id--; val[k] = 0;
}
void writePerm( ) {
   int i;
   for(i=0; i<n; ++i) printf("%c ", letters[val[i]]);
   printf("\n"); nPerm++;
}
int getLetters( ) {
   char tmp[99], i, k;
   printf("輸入字母群: ");
   fgets(tmp, 99, stdin); if(feof(stdin)) return -1;
   k=0;
   for(i=0; i< strlen(tmp); ++i) {
      if(tmp[i] == '\n') break; /* End Of Line */
      if(tmp[i] == ' ') continue; /* ignore blank*/
      val[k] = 0;
      letters[k++] = tmp[i];
   }
   return k;
}