II plus III minus I

##</code><code>##

IV

##</code><code>##

#!perl -lp
map{$_.=(!y/IVXLC/XLCDM/,I,II,III,IV,V,VI,VII,VIII,IX)[$&]while s/\d//;$$_=$n++}@R=0..3999;
y/mp/-+/;s/\w+/${$&}/g;$_=$R[eval]

##</code><code>##

#!perl -lp
# r() converts an arabic number (1..3999 or -3999..-1) to a roman numeral
# using a non-destructive variation of Ton's magic formula (HART).
sub r{my$s;($s.=5x$_*8%29628)=~y$IVCXL426(-:$XLMCDIVX$dfor/./g;$s}
y/iul-z/-$+/d;                 # Step 1: convert plus and minus to +$ and -$
s''$';                         # Step 1: prepend $
$$_=r(),$$$_=$_ for-3999..-1;  # Step 2: build two sets of symbolic references
$_=${+eval};                   # Step 3: eval the expression

##</code><code>##

#!perl -lp040
$s=/m/
if/u/;($y=I1V5X10L50C100D500M1000IV4IX9XL40XC90CD400CM900)=~/$&/,$i=$t+=$s^"$;">($;=$')?-$;:$;while
s/.$//}{1while$y=~/(\D+)$i/&&$t>=$i?($_.=$1,$t-=$i):$i--

##</code><code>##

#!perl -lp
@@{@@=map{$_,$_.0,$_*100}4,5,9,10}=qw(IV XL CD V L D IX XC CM X C M);for$~(@@){s/$@{$~}/"I "x$~/ge}s/I//while s/m\w* +I/m /;$~=y/I//cd;s/I{$~}/$@{$~}||$&/gewhile$~--

##</code><code>##

    { in => "MD plus I\n",
      out => 'MDI' . "\n" },
    { in => "MD minus I\n",
      out => 'MCDXCIX' . "\n" },

##</code><code>##

#!perl -lp
$==$_,s!.!y$IVCXL91-I0$XLMCDXVIII$dfor$_[$=].=4x$&%1859^7;5!egfor+0..3999;@&{@_}=0..@_;y/il-z/-+/d;s/\w+/$&{$&}/g;$_=$_[eval]

##</code><code>##

#!perl -lp
s!.!y$IVCXL91-I0$XLMCDXVIII$dfor$X[$_].=4x$&%1859^7!egfor+0..3999;@Y{@X}=0..@X;y/m/-/;s/\w+/+$Y{$&}/g;$_=$X[eval]

##</code><code>##

#!perl -lp
map{y/IVXLC/XLCDM/,s!\d!$&^4?$&^9?V x($&>3).I x($&%5):IX:IV!ewhile//;$$_=$n++}@d=0..3999;y/m/-/;s/\w+/+${$&}/g;$_=$d[eval]

##</code><code>##

#!perl -lp
sub'_{$;=0;($;.=5x$_*8%29628)=~y$IVCXL426.-X$XLMCDIVX$dfor/./g;$;}y;mp;-+;;s>\w+>(grep$&eq&_,1..1e4)[0]>eg;$_=_$_=eval

##</code><code>##

#!perl -lp
@%=map{my$a;s/./y!IVCXL91-80!XLMCDXVIII!dfor$a.=4x$&%1859^7/eg;$$a=$/--;$a}0..3999;y/i/-/;s/\w+/${$&}/g;$_=$%[-eval]

##</code><code>##

#!perl -pl
y/i-z/-+/s;for$a(1..4e3){$a=~s#.#($n[$a].=4x$&%1859^7)=~y$IVCXL91-I0$XLMCDXVIII$d;s/\b$n[$a]\b/$a/g#ge}$_=$n[eval]

##</code><code>##

#!perl -pl
@;=map{$a=0;($a.=4x$_%1859^7)=~y!IVCXL91-80!XLMCDXVIII!dfor/./g;$$a=$_;$a}s''$'>y/isl-{/-$+
/..3999;$_=$;[eval]

##</code><code>##

#!perl -pl
s|.|y;CLXVI624.-=;MDCLXXVI;dfor$$_.=5x$&*8%29628;$&|ge,$$$_=$_^Kfor-4e3..o;s;\w+;${$&}|$&&'-';ge;$_=${+eval}

##</code><code>##

#!perl -lp
y,iul-~,-$+,d,$_=eval,${$@}=1..!s/./y@IVCXL91-:0@XLMCDXVIII@dfor$@.=4x$&%1859^7/egfor$...3999,u.$_;$_=$@

##</code><code>##

#!perl -pl
$_=${s!.!y$XLIVC246,-:$CDXLMVIX$dfor$$_.=8x$&*5%29628;$$$_=$_!gefor-4e3..s''$'/y/isl-~/-$+/d;eval}

##</code><code>##

#!perl -pl
s!.!y$IVCXL426(-:$XLMCDIVX$dfor$$_.=5x$&*8%29628;$$$_=$_!egfor-4e3..y/iul-}/-$+ /%s''$';*_=eval