quicksort.c

/*
 * 
 * compile: gcc quicksort.c
 * test: ./a.out
 *
 */

#include <stdio.h>

enum { SIZE = 9 };

void quicksort(int *target, int left, int right) {
  if(left >= right) return;
  int i = left, j = right;
  int tmp, pivot = target[i];
  for(;;) {
    while(target[i] < pivot) i++;
    while(pivot < target[j]) j--;
    if(i >= j) break;
    tmp = target[i]; target[i] = target[j]; target[j] = tmp;
    i++; j--;
  }
  quicksort(target, left, i-1);
  quicksort(target, j+1, right);
}

int main() {
  int i, array[SIZE] = { 2, 6, 3, 8, 5, 4, 1, 9, 7 };

  quicksort(array, 0, SIZE-1);

  for(i=0; i<SIZE; i++)
    printf("%d ", array[i]);
  printf("\n");
}

quicksort.tex

%
% test: latex quicksrot.tex
%

\makeatletter

% new if and new counts
\newif\if@q@loop@
\newcount\q@i
\newcount\q@j
\newcount\q@pivot

% macros for array
\def\array#1#2{\csname #1@#2\endcsname}
\def\defarray#1#2#3{\expandafter\xdef\csname #1@#2\endcsname{#3}}

% quick sort
\def\quicksort#1#2#3{% #1: array name, #2: left, #3:right
  \ifnum#2<#3\relax
    \bgroup
      \q@i#2\q@j#3\relax
      \q@pivot\array{#1}{\the\q@i}%
      \@q@loop@true
      \@whilesw\if@q@loop@\fi{%
        \@whilenum\array{#1}{\the\q@i}<\q@pivot\do{\advance\q@i\@ne}%
        \@whilenum\q@pivot<\array{#1}{\the\q@j}\do{\advance\q@j\m@ne}%
        \ifnum\q@i<\q@j
          \edef\q@tmp{\array{#1}{\the\q@i}}%
          \defarray{#1}{\the\q@i}{\array{#1}{\the\q@j}}%
          \defarray{#1}{\the\q@j}{\q@tmp}%
          \advance\q@i\@ne\advance\q@j\m@ne
        \else
          \@q@loop@false
        \fi}%
      \advance\q@i\m@ne\advance\q@j\@ne
      \edef\q@right{\the\q@i}%
      \quicksort{#1}{#2}{\q@right}%
      \edef\q@left{\the\q@j}%
      \quicksort{#1}{\q@left}{#3}%
    \egroup
  \fi}

% test
\def\numlist{2,6,3,8,5,4,1,9,7}

\@tempcnta\z@\@tempcntb\z@
\@for\member:=\numlist\do{%
  \defarray{test}{\the\@tempcnta}{\member}%
  \advance\@tempcnta\@ne}

\quicksort{test}{0}{8}

\typeout{Result:}
\@whilenum\@tempcnta>\@tempcntb\do{%
  \message{\array{test}{\the\@tempcntb}}%
  \advance\@tempcntb\@ne}

\@@end

quicksort.vim

"
" test: vim -S quicksort.vim
"

" quick sort
function! s:quicksort(target, left, right)
  if a:left >= a:right | return [a:target[a:left]] | endif
  let i = a:left | let j = a:right
  let pivot = a:target[i]
  while 1
    while a:target[i] < pivot | let i += 1 | endwhile
    while pivot < a:target[j] | let j -= 1 | endwhile
    if i >= j | break | endif
    let tmp = a:target[i] | let a:target[i] = a:target[j] | let a:target[j] = tmp
    let i += 1 | let j -= 1
  endwhile
  let l_list = s:quicksort(a:target, a:left, i-1)
  let r_list = s:quicksort(a:target, j+1, a:right)
  return l_list + r_list
endfunction

" test
let list = [ 2, 6, 3, 8, 5, 4, 1, 9, 7 ]
echo "Result:"
echo s:quicksort(list, 0, len(list)-1)

on 100000 value it does not work !!
i have the same problem with my algo