藍影

 // ====================================
// filename: directory.cpp
// author : edison.shih.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

char string[200];
char end_string[200];

// ====================================
// generate length = len directory
void directory(int len)
{           
      memset(string, 'a', len);
      int times=0;
      int i=0, j=0;
      int ptr1=0, ptr2=0;

Label:
      for(i=0; i<26; i++) {
            string[len-1] = 'a' + i;
            printf("%s\n", string);           
      }
      strrev(string);
      ptr1=0;
      while(string[ptr1]=='z') ptr1++;
      if(ptr1!=len) {
            for(j=0; j<ptr1; j++) string[j]='a';
            string[ptr1]++;
            strrev(string);           
            goto Label;
      }
     
}

// ====================================
// main function
int main(int argc, char **argv)
{
      memset(end_string, 200, 'z');     
      clock_t t1, t2;
      t1 = clock();
      for(int i=1; i<=5; i++) directory(i);
      t2 = clock();
      printf("elaspe: %lf\n", (double)(t2-t1)/(double)(CLK_TCK));
     
      return 0;
}
// ====================================