[dave@dave lisp]$ clisp
i
. i i i I i i i i ooooo o ooooooo ooooo ooooo
I I I I I I I I I 8 8 8 8 8 o 8 8
I I \ `+' / I I 8 8 8 8 8 8
I \ `-+-' / I 8 8 8 ooooo 8oooo
\ `-__|__-' / 8 8 8 8 8
`--___|___--' 8 o 8 8 o 8 8
| ooooo 8oooooo ooo8ooo ooooo 8
--------+--------
Welcome to GNU CLISP 2.49 (2010-07-07) <http://clisp.cons.org/>
Code ( taken from Object Oriented Common Lisp )
defun roman-to-decimal (num-list)
(if ( endp num-list)
0
(+ (or
(and (cdr num-list)
(< (numeral-to-decimal (car num-list))
(numeral-to-decimal (cadr num-list)))
(- (numeral-to-decimal (car num-list))))
(numeral-to-decimal (car num-list)))
(roman-to-decimal (cdr num-list)))))
(load "roman-to-decimal.lisp")
[7]> (roman-to-decimal '(M C M L X I X ))
1969
[8]> (trace roman-to-decimal)
;; Tracing function ROMAN-TO-DECIMAL.
(ROMAN-TO-DECIMAL)
[9]> (roman-to-decimal '(M C M L X I X ))
1. Trace: (ROMAN-TO-DECIMAL '(M C M L X I X))
2. Trace: (ROMAN-TO-DECIMAL '(C M L X I X))
3. Trace: (ROMAN-TO-DECIMAL '(M L X I X))
4. Trace: (ROMAN-TO-DECIMAL '(L X I X))
5. Trace: (ROMAN-TO-DECIMAL '(X I X))
6. Trace: (ROMAN-TO-DECIMAL '(I X))
7. Trace: (ROMAN-TO-DECIMAL '(X))
8. Trace: (ROMAN-TO-DECIMAL 'NIL)
8. Trace: ROMAN-TO-DECIMAL ==> 0
7. Trace: ROMAN-TO-DECIMAL ==> 10
6. Trace: ROMAN-TO-DECIMAL ==> 9
5. Trace: ROMAN-TO-DECIMAL ==> 19
4. Trace: ROMAN-TO-DECIMAL ==> 69
3. Trace: ROMAN-TO-DECIMAL ==> 1069
2. Trace: ROMAN-TO-DECIMAL ==> 969
1. Trace: ROMAN-TO-DECIMAL ==> 1969
1969
Haskell
http://www.haskell.org/haskellwiki/Roman_numerals#More-than-one_liner
http://www.cs.york.ac.uk/ftpdir/pub/haskell/contrib/Roman.hs
[dave@dave haskell]$ ghci
GHCi, version 6.12.3: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
Prelude> :l Roman.hs
[1 of 1] Compiling Main ( Roman.hs, interpreted )
Ok, modules loaded: Main.
*Main> fromRoman "MCMLXIX"
1969
Simple Java implementation
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class RomanToDecimal {
public static Map<String, Integer> romanNumberMap = new HashMap<String, Integer>();
static {
// ( (I 1) (V 5) (X 10) (L 50) (C 100) (D 500) (M 1000)))
romanNumberMap.put("I", 1);
romanNumberMap.put("V", 5);
romanNumberMap.put("X", 10);
romanNumberMap.put("L", 50);
romanNumberMap.put("C", 100);
romanNumberMap.put("D", 500);
romanNumberMap.put("M", 1000);
}
public static void main(String[] args) {
roman2dec("IV");
roman2dec("LXIV");
roman2dec("XCVIII");
roman2dec("MCMLXIX");
}
private static int roman2dec(String roman) {
int out = 0;
List<Integer> list = new ArrayList<Integer>();
for (int i = 0; i < roman.length(); i++) {
list.add(romanNumberMap.get(String.valueOf(roman.charAt(i))));
}
System.out.println("list=" + list);
while (list.size() > 0) {
if ((list.size() > 1) && (list.get(0) < list.get(1))) {
out -= list.remove(0);
} else {
out += list.remove(0);
}
System.out.println(" list=" + list + " out=" + out);
}
System.out.println("roman=" + roman + " dec=" + out);
return out;
}
}
list=[1, 5]
list=[5] out=-1
list=[] out=4
roman=IV dec=4
list=[50, 10, 1, 5]
list=[10, 1, 5] out=50
list=[1, 5] out=60
list=[5] out=59
list=[] out=64
roman=LXIV dec=64
list=[10, 100, 5, 1, 1, 1]
list=[100, 5, 1, 1, 1] out=-10
list=[5, 1, 1, 1] out=90
list=[1, 1, 1] out=95
list=[1, 1] out=96
list=[1] out=97
list=[] out=98
roman=XCVIII dec=98
list=[1000, 100, 1000, 50, 10, 1, 10]
list=[100, 1000, 50, 10, 1, 10] out=1000
list=[1000, 50, 10, 1, 10] out=900
list=[50, 10, 1, 10] out=1900
list=[10, 1, 10] out=1950
list=[1, 10] out=1960
list=[10] out=1959
list=[] out=1969
roman=MCMLXIX dec=1969
