Q$1(20$ points$)$: Stack and Queue Application

$3$

Assume that a program reads the following values one at a time into variable $x.$ Value $-99$ is to stop the program exccution.

$20,6,18,6,14,8,12,7,11,15,24,26,30,-99$

Trace the following Java$-$like pseudocode code and write down its output as exactly it would appear on the screen.

Create stack $s$

Create queve $Q$

S$.$ push $(50)$:

Q$.$ enqueue $(50)$ :

Read first input value to $x$;

While $(x,-99)$

i$.$

Switch $(x$:$4)$

$1$

Case $0$: S$,$ push $($X$)$

Exit Switch Statement;

Case $1$: If $($S$.$isEmpty $!=$ true$)$

$.$ top $()$

Printout $("$Stack Element: $+Y)$;

S$.$ pop$()$;

Else Printout "Sorry, stack is empty";

Exit Switch Statement;

Case $2$: Q$.$enqueue $(x)$ ;

Exit Switch Statement;

Case $3$: If $($Q$.$isEmpty $!=$ true$)$

$\{$Y$=$ Q$.$front$()$;

Printout $("$Queue Element: $"+Y)$;

Q$.$ dequeue $()$ ;

$\}$

Else Printout "Sorry, queue is empty";

Exit Switch Statement;

$\}//$end of Switch statement

Read next input value to $x$;

$//$end of While statement

Printout $("$Stack Elements are: $")$;

While $(($S$.$isEmpty $!=$ true$)$

$1Y=$ s$.$top$()$

Printout on newline $(Y)$;

S$.$pop$()$;

$1$

Printout $("$Queue Elements are: $")$;

While $(($Q$.$isEmpty $$ true$)$

& $Y=$ Q$.$front $()$

Printout on newline $(Y)$;

Q$.$ dequeue $()$ ;

$1$