In java programming: User

class Quicksort

$\{$

$//$ Set up a call to the actual Quicksort method.

static void qsort$($char items$[])$

$\{$

qs$($items$,0,$ items.length $-1)$;

$\}$

$//$ A recursive version of Quicksort for characters.

private static void qs$($char items$[],$ int left, int right$)$

$\{$

int i$,$ j;

char x$,$ y;

i $=$ left; j $=$ right;

x $=$ items$[($left $+$ right$)/2]$;

do

$\{$

while$(($items$[$i$]<$ x$)$ && $($i $<$ right$))$ i$++$;

while$(($x $<$ items$[$j$])$ && $($j $>$ left$))$ j$--$;

if$($i $<=$ j$)$

$\{$

y $=$ items$[$i$]$;

items$[$i$]=$ items$[$j$]$;

items$[$j$]=$ y;

i$++$; j$--$;

$\}$

$\}$ while$($i $<=$ j$)$;

if$($left $<$ j$)$ qs$($items$,$ left, j$)$;

if$($i $<$ right$)$ qs$($items$,$ i$,$ right$)$;

$\}$

$\}$

class QSDemo

$\{$

public static void main$($String args$[])$

$\{$

char a$[]=\{\text{'}$d$\text{'},\text{'}$x$\text{'},\text{'}$a$\text{'},\text{'}$r$\text{'},\text{'}$p$\text{'},\text{'}$j$\text{'},\text{'}$i$\text{'},\}$;

int i;

System.out.print$("$Original array: $")$;

for$($i $=0$; i $<$ a$.$length; i$++)$

System.out.print$($a$[$i$])$;

System.out.println$()$;

$//$ now, sort the array

Quicksort.qsort$($a$)$;

System.out.print$("$Sorted array: $")$;

for$($i $=0$; i $<$ a$.$length; i$++)$

System.out.print$($a$[$i$])$;

$\}$

$\}$ A$.$ Explain how the characters are sorted in the program.

B$.$ Explain why QuickSort program is a recursion.