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

#define MAX 255

struct freq {int ch;int count;};

struct freq * f[MAX];
int fp;

incFreq(int ch)
{  int i;
   i=0;
   while(i<fp)
    if(f[i]->ch==ch)
    {  f[i]->count = f[i]->count+1;
       return;
    }
    else
     i = i+1;
   if(fp==MAX)
   {  printf("more than %d different characters\n",MAX);
      exit(0);
   }
   f[fp] = (struct freq *)malloc(sizeof(struct freq));
   f[fp]->ch = ch;
   f[fp]->count = 1;
   fp = fp+1;
}

showFreq()
{  int i;
   i = 0;
   while(i<fp)
   {  printf("%c : %d\n, ",f[i]->ch,f[i]->count);
      i = i+1;
   }
   printf("\n");
}

swap(struct freq * a[],int i,int j)
{  struct freq *t;
   t = a[i];
   a[i] = a[j];
   a[j] = t;
}

int partition(struct freq * a[],int l,int r)
{  int i,j,p;
   i = l;
   j = r;
   p = a[(i+j)/2]->count;
   while(i<=j)
   {  while(a[i]->count<p)
       i = i+1;
      while(a[j]->count>p)
       j = j-1;
      if(i<=j)
      {  swap(a,i,j);
         i = i+1;
         j = j-1;
      }
   }
   return i;
}

quicksort(struct freq * a[],int l,int r)
{  int p;
   if(l<r)
   {  p = partition(a,l,r);
      quicksort(a,l,p-1);
      quicksort(a,p,r);
   }
}
   
main(int argc,char ** argv)
{  int ch;
   FILE * fin;
   if((fin=fopen(argv[1],"r"))==NULL)
   {  printf("can't open %s\n",argv[1]);
      exit(0);
   }
   fp = 0;
   ch = getc(fin);
   while(ch!=EOF)
   {  incFreq(ch);
      ch = getc(fin);
   }
   fclose(fin);
   showFreq();
   quicksort(f,0,fp-1);
   showFreq();
}