pythonPrograms/rankingStudents.py at master · Priyansi/pythonPrograms · GitHub

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#!python3
importitertoolsasit

GREATER_THAN='>'
NEWLINE='\n'


defrelation(A, B):
ifall([a>bfora, binzip(A, B)]):
return">"
elifall([a<bfora, binzip(A, B)]):
return"<"
return"#"


defread_file(FILENAME):
roll_marks= {}
withopen(FILENAME, 'r') asf:
forlineinf.readlines():
roll, *marks=line.split()
roll_marks[roll] = [int(mark) formarkinmarks]
returnroll_marks


defall_relations(FILENAME):
roll_marks=read_file(FILENAME)
rolls=roll_marks.keys()
rels=set()
forroll1, roll2init.combinations(rolls, 2):
rel=relation(roll_marks[roll1], roll_marks[roll2])
ifrel==">":
rels.add(roll1+roll2)
elifrel=="<":
rels.add(roll2+roll1)
returnrels


defall_removables(rels):
defis_removable(first, middle, second):
returnfirst+middleinrelsandmiddle+secondinrels

firsts=set([rel[0] forrelinrels])
seconds=set([rel[1] forrelinrels])
both=firsts&seconds
returnset(first+secondforfirstinfirstsforsecondinsecondsiffirst+secondinrelsformiddleinbothifis_removable(first, middle, second))


defstart_middle_end_rels(minimal):
firsts= [rel[0] forrelinminimal]
seconds= [rel[1] forrelinminimal]
start_rels, end_rels, middle_rels=list(), list(), list()
forrelinminimal:
ifrel[0] insecondsandrel[1] infirsts:
middle_rels.append(rel)
else:
ifrel[0] notinseconds:
start_rels.append(rel)
ifrel[1] notinfirsts:
end_rels.append(rel)
returnstart_rels, middle_rels, end_rels


defremove_common_start_end_rels(orders, start_rels, end_rels):
forrelinstart_rels:
forxinend_rels:
ifrel[1] ==x[0]:
orders.append(rel+x[1])
start_rels.remove(rel)
returnorders, start_rels, end_rels


defremove_same_start_end_rels(orders, start_rels, end_rels):
forrelinstart_rels:
ifrelinend_rels:
orders.append(rel)
start_rels.remove(rel)
end_rels.remove(rel)
returnorders, start_rels, end_rels


defmake_partial_orders(orders, start_rels, middle_rels, end_rels):
deffind_next_rel(rel):
formiddle_relinmiddle_rels:
ifrel[-1] ==middle_rel[0]:
returnmiddle_rel

firsts_of_end_orders= [end_rel[0] forend_relinend_rels]
forrelinstart_rels:
partial_order=rel
next_rel=find_next_rel(rel)
whilenext_rel[1] notinfirsts_of_end_orders:
partial_order+=next_rel[1]
next_rel=find_next_rel(next_rel)
end_order=end_rels[firsts_of_end_orders.index(next_rel[1])]
orders.append(partial_order+end_order)
returnorders


defpartial_orders(FILENAME):
rels=all_relations(FILENAME)
minimal=rels^all_removables(rels)
orders= []
start_rels, middle_rels, end_rels=start_middle_end_rels(minimal)
orders, start_rels, end_rels=remove_same_start_end_rels(
orders, start_rels, end_rels)
orders, start_rels, end_rels=remove_common_start_end_rels(
orders, start_rels, end_rels)
returnNEWLINE.join(GREATER_THAN.join(rollforrollinpartial_order) forpartial_orderinmake_partial_orders(orders, start_rels, middle_rels, end_rels))


print(partial_orders('roll_and_marks.txt'))