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Dinesman's multiple-dwelling problem: Difference between revisions
Dinesman's multiple-dwelling problem (view source)
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=={{header|Python}}==
This example parses the statement of the problem as given and allows some variability such as the number of people, floors and constraints can be varied although the type of constraints allowed and the sentence structure is limited
===Setup===
Parsing is done with the aid of the multi-line regular expression at the head of the program.
<lang python>import re
from itertools import product
problem_re = re.compile(r"""(?msx)(?:
# Multiple names of form n1, n2, n3, ... , and nK
(?P<namelist> [a-zA-Z]+ (?: , \s+ [a-zA-Z]+)* (?: ,? \s+ and) \s+ [a-zA-Z]+ )
# Flexible floor count (2 to 10 floors)
| (?: .* house \s+ that \s+ contains \s+ only \s+
(?P<floorcount> two|three|four|five|six|seven|eight|nine|ten ) \s+ floors \s* \.)
# Constraint: "does not live on the n'th floor"
|(?: (?P<not_live> \b [a-zA-Z]+ \s+ does \s+ not \s+ live \s+ on \s+ the \s+
(?: top|bottom|first|second|third|fourth|fifth|sixth|seventh|eighth|ninth|tenth) \s+ floor \s* \. ))
# Constraint: "does not live on either the I'th or the J'th [ or the K'th ...] floor
|(?P<not_either> \b [a-zA-Z]+ \s+ does \s+ not \s+ live \s+ on \s+ either
(?: \s+ (?: or \s+)? the \s+
(?: top|bottom|first|second|third|fourth|fifth|sixth|seventh|eighth|ninth|tenth))+ \s+ floor \s* \. )
# Constraint: "P1 lives on a higher/lower floor than P2 does"
|(?P<hi_lower> \b [a-zA-Z]+ \s+ lives \s+ on \s+ a \s (?: higher|lower)
\s+ floor \s+ than (?: \s+ does) \s+ [a-zA-Z]+ \s* \. )
# Constraint: "P1 does/does not live on a floor adjacent to P2's"
|(?P<adjacency> \b [a-zA-Z]+ \s+ does (?:\s+ not)? \s+ live \s+ on \s+ a \s+
floor \s+ adjacent \s+ to \s+ [a-zA-Z]+ (?: 's )? \s* \. )
# Ask for the solution
|(?P<question> Where \s+ does \s+ everyone \s+ live \s* \?)
)
""")
names, lennames = None, None
floors = None
constraint_expr = 'len(set(alloc)) == lennames' # Start with all people on different floors
def do_namelist(txt):
" E.g. 'Baker, Cooper, Fletcher, Miller, and Smith'"
global names, lennames
names = txt.replace(' and ', ' ').split(', ')
lennames = len(names)
def do_floorcount(txt):
" E.g. 'five'"
global floors
floors = '||two|three|four|five|six|seven|eight|nine|ten'.split('|').index(txt)
def do_not_live(txt):
" E.g. 'Baker does not live on the top floor.'"
global constraint_expr
t = txt.strip().split()
who, floor = t[0], t[-2]
w, f = (names.index(who),
('|first|second|third|fourth|fifth|sixth|' +
'seventh|eighth|ninth|tenth|top|bottom|').split('|').index(floor)
)
if f == 11: f = floors
if f == 12: f = 1
constraint_expr += ' and alloc[%i] != %i' % (w, f)
def do_not_either(txt):
" E.g. 'Fletcher does not live on either the top or the bottom floor.'"
global constraint_expr
t = txt.replace(' or ', ' ').replace(' the ', ' ').strip().split()
who, floor = t[0], t[6:-1]
w, fl = (names.index(who),
[('|first|second|third|fourth|fifth|sixth|' +
'seventh|eighth|ninth|tenth|top|bottom|').split('|').index(f)
for f in floor]
)
for f in fl:
if f == 11: f = floors
if f == 12: f = 1
constraint_expr += ' and alloc[%i] != %i' % (w, f)
def do_hi_lower(txt):
" E.g. 'Miller lives on a higher floor than does Cooper.'"
global constraint_expr
t = txt.replace('.', '').strip().split()
name_indices = [names.index(who) for who in (t[0], t[-1])]
if 'lower' in t:
name_indices = name_indices[::-1]
constraint_expr += ' and alloc[%i] > alloc[%i]' % tuple(name_indices)
def do_adjacency(txt):
''' E.g. "Smith does not live on a floor adjacent to Fletcher's."'''
global constraint_expr
t = txt.replace('.', '').replace("'s", '').strip().split()
name_indices = [names.index(who) for who in (t[0], t[-1])]
constraint_expr += ' and abs(alloc[%i] - alloc[%i]) > 1' % tuple(name_indices)
def do_question(txt):
global constraint_expr, names, lennames
exec_txt = '''
for alloc in product(range(1,floors+1), repeat=len(names)):
if %s:
break
else:
alloc = None
''' % constraint_expr
exec(exec_txt, globals(), locals())
a = locals()['alloc']
if a:
output= ['Floors are numbered from 1 to %i inclusive.' % floors]
for a2n in zip(a, names):
output += [' Floor %i is occupied by %s' % a2n]
output.sort(reverse=True)
print('\n'.join(output))
else:
print('No solution found.')
print()
handler = {
'namelist': do_namelist,
'floorcount': do_floorcount,
'not_live': do_not_live,
'not_either': do_not_either,
'hi_lower': do_hi_lower,
'adjacency': do_adjacency,
'question': do_question,
}
def parse_and_solve(problem):
p = re.sub(r'\s+', ' ', problem).strip()
for x in problem_re.finditer(p):
groupname, txt = [(k,v) for k,v in x.groupdict().items() if v][0]
#print ("%r, %r" % (groupname, txt))
handler[groupname](txt)</lang>
===Problem statement===
This is not much more than calling a function on the text of the problem!
<lang python>if __name__ == '__main__':
parse_and_solve("""
Baker, Cooper, Fletcher, Miller, and Smith
live on different floors of an apartment house that contains
only five floors. Baker does not live on the top floor. Cooper
does not live on the bottom floor. Fletcher does not live on
either the top or the bottom floor. Miller lives on a higher
floor than does Cooper. Smith does not live on a floor
adjacent to Fletcher's. Fletcher does not live on a floor
adjacent to Cooper's. Where does everyone live?""")
print('# Add another person with more constraints and more floors:')
parse_and_solve("""
Baker, Cooper, Fletcher, Miller, Guinan, and Smith
live on different floors of an apartment house that contains
only seven floors. Guinan does not live on either the top or the third or the fourth floor.
Baker does not live on the top floor. Cooper
does not live on the bottom floor. Fletcher does not live on
either the top or the bottom floor. Miller lives on a higher
floor than does Cooper. Smith does not live on a floor
adjacent to Fletcher's. Fletcher does not live on a floor
adjacent to Cooper's. Where does everyone live?""")</lang>
===Output===
This shows the output from the original problem and then for another, slightly different problem to cover some of the variability asked for in the task.
<pre>Floors are numbered from 1 to 5 inclusive.
Floor 5 is occupied by Miller
Floor 4 is occupied by Fletcher
Floor 3 is occupied by Baker
Floor 2 is occupied by Cooper
Floor 1 is occupied by Smith
# Add another person with more constraints and more floors:
Floors are numbered from 1 to 7 inclusive.
Floor 7 is occupied by Smith
Floor 6 is occupied by Guinan
Floor 4 is occupied by Fletcher
Floor 3 is occupied by Miller
Floor 2 is occupied by Cooper
Floor 1 is occupied by Baker
</pre>
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