# RomanSol.py
# the 2016sp cs 1110 profs (cs-1110profs-l@cornell.edu)
# Feb 25, 2016
""" A framework for checking Roman numeral strings and their
value."""
def AllCharsOK(R):
"""Returns True if every character in R is in
'MDCLXVI' and returns False if not.
PreC: R is a string of length > 0."""
NumGoodChars = (R.count('I') + R.count('V') + R.count('X') +
R.count('L') + R.count('C') + R.count('D') +
R.count('M'))
return NumGoodChars==len(R)
# Alternate implementation
def AllCharsOK2(R):
"""Returns True if every character in R is in
'MDCLXVI' and returns False if not.
PreC: R is a string of length > 0"""
roman_chars = 'MDCLXVI'
for c in R:
if c not in roman_chars:
return False
return True
def AllFreqsOK(R):
""" Returns True if R is a frequency-legal string"
PreC: R is a string of length > 0
"""
B = ( R.count('M')<=3 and R.count('D')<=1 and R.count('C')<=3 and
R.count('L')<=1 and R.count('X')<=3 and R.count('V')<=1 and
R.count('I')<=3)
return B
# alternate implementation
def AllFreqsOK2(R):
""" Returns True if R is a frequency-legal string"
PreC: R is a string of length > 0
"""
at_most_three='MCXI'
at_most_one='DLV'
for c in at_most_three:
if R.count(c) > 3:
return False
for c in at_most_one:
if R.count(c) > 1:
return False
# all conditions above passed
return True
def SingleOK(c,s,R):
""" Returns True if c is not in R or if c is in R but
not preceded by any character in s. Otherwise, False is returned,
PreC: c is a character, s is a nonempty string, R is a nonempty string,
and c is not in s.
"""
for x in s:
if (x in R) and (R.rfind(c) > R.find(x)):
return False
# if here, there isn't any x in R that occurs before the last c.
return True
# Note: rfind is just like find except it looks for the location
# of the last occurrence.
# alternate solution more like what's given in the hints
def SingleOK2(c,s,R):
""" Returns True if c is not in R or if c is in R but
not preceded by any character in s. Otherwise, False is returned,
PreC: c is a character, s is a nonempty string, R is a nonempty string,
and c is not in s.
"""
if c not in R:
return True
else:
for character in s:
if character in R and R.rfind(c) > R.find(character):
return False
return True
def AllSinglesOK(R):
"""Returns True if and only if R is an single-legal string.
PreC: R is a non-null string.
"""
M_ok = SingleOK('M','DLXVI',R)
D_ok = SingleOK('D','LXVI',R)
C_ok = SingleOK('C','LVI',R)
L_ok = SingleOK('L','VI',R)
X_ok = SingleOK('X','V',R)
return M_ok and D_ok and C_ok and L_ok and X_ok
def DoubleOK(s,R):
""" Returns True if s is not in R or if s occurs once in R
and the first occurrence of s[0] is the first occurrence of s.
PreC: s is a length-2 string and R is a nonempty string.
"""
if R.count(s)==0:
return True
else:
return R.find(s)==R.find(s[0]) and R.count(s)==1
def AllDoublesOK(R):
"""Returns True if and only if R is a double-legal string.
PreC: R is a non-null string.
"""
C_ok = DoubleOK('CD',R) and DoubleOK('CM',R)
X_ok = DoubleOK('XL',R) and DoubleOK('XC',R)
I_ok = DoubleOK('IV',R) and DoubleOK('IX',R)
return C_ok and X_ok and I_ok
def Value(R):
""" Returns an int that is the value of R
PreC: R is a Roman numeral string.
"""
# The preliminary value
s = (R.count('M')*1000 + R.count('D')*500 + R.count('C')*100 + R.count('L')*50+
R.count('X')*10 + R.count('V')*5 + R.count('I'))
# The adjustments...
# in acceptable strings, there can't be both 'CM' and 'CD'
if R.find('CM')>=0 or R.find('CD')>=0:
s = s-200
# in acceptable strings, there can't be both 'XL' and 'XC'
if R.find('XL')>=0 or R.find('XC')>=0:
s = s - 20
# in acceptable strings, there can't be both 'IX' and 'IV'
if R.find('IX')>=0 or R.find('IV')>=0:
s = s-2
return s
if __name__ == '__main__':
# an alternate testing scheme using lists of lists and lists of functions
list_debug=True
if list_debug:
print '(partially) testing AllChars functions'
answers = [['IXIIIDDCM', True],['3X', False],['XXX', True]]
for answer in answers:
for fn in [AllCharsOK, AllCharsOK2]:
response = fn(answer[0])
if response != answer[1]:
print "function", fn, ", input was", answer[0], "but output was",str(response)
print '(partially) testing AllFreqs functions'
answers = [ ['IXIILDMVX', True],
['MM1984XVI', True],
['XXXX', False],
['D3D', False]]
for answer in answers:
for fn in [AllFreqsOK, AllFreqsOK2]:
response = fn(answer[0])
if response != answer[1]:
print "function", fn, ", input was", answer[0], "but output was",str(response)
print '(partially) testing SingleOK functions'
answers = [ ['C', 'LVI', 'MDV', True],
['C', 'LVI', 'MCCV', True],
['C', 'LVI', 'MCVCV', False],
['M', 'DLXVI', 'CIMVM', False],
['M', 'DLXVI', 'MCMXIV', True]]
for answer in answers:
for fn in [SingleOK, SingleOK2]:
response = fn(answer[0], answer[1], answer[2])
if response != answer[3]:
print "function", fn, ", input was", answer[0], answer[1], answer[2], "but output was",str(response)
print '(partially) testing AllSinglesOK functions'
answers = [ ['MCMXIV', True],
['CIMVM', False]]
for answer in answers:
for fn in [AllSinglesOK]:
response = fn(answer[0])
if response != answer[1]:
print "function", fn, ", input was", answer[0], "but output was",str(response)
print '(partially) testing DoubleOK functions'
answers = [ ['CM','MCMXC', True],
['CM','MCX', True],
['CM', 'MCXCM', False]]
for answer in answers:
for fn in [DoubleOK]:
response = fn(answer[0], answer[1])
if response != answer[2]:
print "function", fn, ", input was", answer[0],answer[1], "but output was",str(response)
print 'all tests done'
# the regular "test on the command-line" testing scheme
R = raw_input('Enter a Roman Numeral String (do not surround with quotes): ')
print 'AllCharsOK(R) is ',AllCharsOK(R)
print 'AllFreqsOK(R) is ',AllFreqsOK(R)
print 'AllSinglesOK(R) is ',AllSinglesOK(R)
print 'AllDoublesOK(R) is ',AllDoublesOK(R)
OK = AllCharsOK(R) and AllFreqsOK(R) and AllSinglesOK(R) and AllDoublesOK(R)
if OK:
print 'Value = %1d' % Value(R)
else:
print 'Not a valid Roman numeral string.'