pep-material: progs/roman_sol.scala@d39b8733c6ea (annotated)

108 d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	1	// Part 1 about Roman Numerals
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	2	//=============================
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	3
104 07780accd5df updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: diff changeset	4	abstract class RomanDigit
07780accd5df updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: diff changeset	5	case object I extends RomanDigit
07780accd5df updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: diff changeset	6	case object V extends RomanDigit
07780accd5df updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: diff changeset	7	case object X extends RomanDigit
07780accd5df updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: diff changeset	8	case object L extends RomanDigit
07780accd5df updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: diff changeset	9	case object C extends RomanDigit
07780accd5df updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: diff changeset	10	case object D extends RomanDigit
07780accd5df updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: diff changeset	11	case object M extends RomanDigit
105 67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	12
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	13	type RomanNumeral = List[RomanDigit]
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	14
108 d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	15
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	16	// (1) First write a polymorphic function that recursively
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	17	// transforms a list of options into an option of a list.
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	18	// As soon as a None is inside the list, the result is None.
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	19	// Otherwise produce a list of all Some's appended.
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	20
105 67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	21	def optionlist[A](xs: List[Option[A]]): Option[List[A]] = xs match {
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	22	case Nil => Some(Nil)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	23	case x::xs => (x, optionlist(xs)) match {
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	24	case (None, _) => None
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	25	case (_, None) => None
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	26	case (Some(y), Some(ys)) => Some(y::ys)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	27	}
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	28	}
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	29
108 d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	30	optionlist(List(Some(1), Some(2), Some(3)))
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	31	optionlist(List(Some(1), None, Some(3)))
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	32	optionlist(List())
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	33
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	34	// (2) Write a function first a function that converts a character
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	35	// into a roman digit (if possible). Then convert a string into
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	36	// a roman numeral (if possible). If this is not possible, the functions
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	37	// should return None.
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	38
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	39	def Char2RomanDigit(c: Char): Option[RomanDigit] = c match {
105 67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	40	case 'I' => Some(I)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	41	case 'V' => Some(V)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	42	case 'X' => Some(X)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	43	case 'L' => Some(L)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	44	case 'C' => Some(C)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	45	case 'D' => Some(D)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	46	case 'M' => Some(M)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	47	case _ => None
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	48	}
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	49
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	50	def String2RomanNumeral(s: String) : Option[RomanNumeral] =
108 d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	51	optionlist(s.toList.map(Char2RomanDigit))
105 67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	52
108 d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	53	// some test cases
105 67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	54	String2RomanNumeral("IIII")
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	55	String2RomanNumeral("IV")
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	56	String2RomanNumeral("VI")
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	57	String2RomanNumeral("IX")
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	58	String2RomanNumeral("MCMLXXIX")
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	59	String2RomanNumeral("MCMXLIV")
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	60	String2RomanNumeral("M C M X L I V") // None
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	61
108 d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	62
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	63	// (3) Write a recursive function RomanNumral2Int that converts a
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	64	// RomanNumeral into an integer.
105 67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	65
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	66	def RomanNumeral2Int(rs: RomanNumeral): Int = rs match {
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	67	case Nil => 0
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	68	case M::r => 1000 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	69	case C::M::r => 900 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	70	case D::r => 500 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	71	case C::D::r => 400 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	72	case C::r => 100 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	73	case X::C::r => 90 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	74	case L::r => 50 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	75	case X::L::r => 40 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	76	case X::r => 10 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	77	case I::X::r => 9 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	78	case V::r => 5 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	79	case I::V::r => 4 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	80	case I::r => 1 + RomanNumeral2Int(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	81	}
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	82
108 d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	83	// some test cases
105 67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	84	RomanNumeral2Int(List(I,I,I,I)) // 4
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	85	RomanNumeral2Int(List(I,V)) // 4
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	86	RomanNumeral2Int(List(V,I)) // 6
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	87	RomanNumeral2Int(List(I,X)) // 9
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	88	RomanNumeral2Int(List(M,C,M,L,X,X,I,X)) // 1979
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	89	RomanNumeral2Int(List(M,C,M,X,L,I,V)) // 1944
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	90
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	91
108 d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	92	// (4) Write a function that converts a string (containing
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	93	// a roman numeral) into an integer (if possible). If not
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	94	// this is not possible, the functions should return None.
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	95
105 67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	96	def String2Int(s: String): Option[Int] =
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	97	String2RomanNumeral(s).map(RomanNumeral2Int(_))
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	98
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	99
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	100	String2Int("IIII") // 4 invalid
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	101	String2Int("IV") // 4
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	102	String2Int("VI") // 6
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	103	String2Int("IX") // 9
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	104	String2Int("MCMLXXIX") // 1979
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	105	String2Int("MCMXLIV") // 1944
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	106	String2Int("") // 0
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	107	String2Int("MDCLXI") // 1661
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	108	String2Int("MMMCMXCIX") // 3999
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	109	String2Int("XLVIII") // 48
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	110	String2Int("MMVIII") // 2008
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	111
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	112	String2Int("MMXI") // 2011
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	113	String2Int("MIM") // 1999
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	114	String2Int("MCMLVI") // 1956
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	115	String2Int("XXCIII") // ?? 103 / 83
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	116	String2Int("LXXIIX") // ?? 80 / 78
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	117	String2Int("IIIIX") // ?? 12 invalid
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	118	String2Int("IIXX") // ?? 20 / 18 invalid
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	119
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	120	String2Int("III") // 3
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	121	String2Int("XXX") // 30
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	122	String2Int("CCC") // 300
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	123	String2Int("MMM") // 3000
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	124	String2Int("VII") // 7
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	125	String2Int("LXVI") // 66
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	126	String2Int("CL") // 150
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	127	String2Int("MCC") // 1200
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	128	String2Int("IV") // 4
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	129	String2Int("IX") // 9
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	130	String2Int("XC") // 90
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	131	String2Int("ICM") // ?? 901
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	132	String2Int("CIM") // ?? 899
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	133	String2Int("MDCLXVI") // 1666
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	134
108 d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	135	String2Int("VIV") // 9, but should be written as IX
105 67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	136	String2Int("IVX") // 14 invalid
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	137
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	138	// error cases
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	139	String2Int("MC?I")
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	140	String2Int("abc")
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	141
108 d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	142	// (5) The file roman.txt contains a list of roman numerals.
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	143	// Read in these numerals, convert them into integers and then
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	144	// add them all up.
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	145
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	146	import io.Source
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	147	import scala.util._
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	148
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	149	// function for reading files:
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	150	// Source.fromFile("file_name")("ISO-8859-9")
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	151
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	152	def addromanfile(filename: String) = {
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	153	val lines = Source.fromFile(filename)("ISO-8859-9").getLines.toList.map(_.trim)
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	154	lines.map(String2Int(_)).flatten.sum
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	155	}
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	156
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	157
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	158	addromanfile("roman.txt")
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	159
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	160
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	161
d39b8733c6ea updated Christian Urban <urbanc@in.tum.de> parents: 105 diff changeset	162
105 67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	163
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	164	def runsAllowed(r: RomanDigit) = r match {
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	165	case I \| X \| C \| M => true
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	166	case V \| L \| D => false
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	167	}
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	168
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	169	def norunsAllowed(r: RomanDigit) = !runsAllowed(r)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	170
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	171
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	172	def isValidNumeral(digitList: RomanNumeral): Bool = digitList match {
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	173
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	174	// empty list is valid
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	175	case Nil => true
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	176
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	177	// a following digit that is equal or larger is an error
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	178	case d1::d2::_ if (d1 <= d2) => false
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	179
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	180	// A single digit is always allowed
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	181	case _::ds => isValidNumeral(ds)
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	182
67ce930b5935 updated Christian Urban <christian dot urban at kcl dot ac dot uk> parents: 104 diff changeset	183	}

author	Christian Urban <urbanc@in.tum.de>
	Thu, 26 Jan 2017 01:43:31 +0000
changeset 108	d39b8733c6ea
parent 105	67ce930b5935
child 109	293ea84d82ca
permissions	-rw-r--r--