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SATEncoding.py
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SATEncoding.py
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from copy import deepcopy
import copy
input = open("Test_Cases/input5.txt",'r')
output = open("Test_Cases/output.txt",'w')
friends = []
enemies = []
list_clauses = []
symbols = set()
file_logs = ""
global guests
global tables
def Cond1():
for i in xrange(1,guests+1):
clause = []
alt_clause = []
for j in xrange(1,tables+1):
clause.append("~X" + "-" + str(i) + "-" + str(j))
alt_clause.append("X"+ "-" + str(i)+ "-" +str(j))
#symbols.add("~X"+str(i)+str(j))
symbols.add("X"+ "-" + str(i) + "-" + str(j))
list_clauses.append(alt_clause)
if tables > 1:
list_clauses.append(clause)
def Cond2():
for f in friends:
a,b = f
for i in xrange(1,tables+1):
clause = []
alt_clause = []
clause.extend(["~X"+ "-" +str(a)+ "-" +str(i),"X" + "-" + str(b) + "-" +str(i)])
alt_clause.extend(["X"+ "-" + str(a) + "-" +str(i),"~X"+ "-"+ str(b)+"-"+ str(i)])
#symbols.add("~X"+str(a)+str(i))
symbols.add("X"+ "-" +str(b)+ "-" +str(i))
symbols.add("X"+ "-" +str(a)+ "-" +str(i))
#symbols.add("~X"+str(b)+str(i))
list_clauses.append(clause)
list_clauses.append(alt_clause)
def Cond3():
for e in enemies:
a,b = e
for i in xrange(1,tables+1):
clause = []
clause.extend(["~X"+ "-" +str(a)+ "-"+str(i),"~X"+ "-"+ str(b)+ "-" +str(i)])
#symbols.add("~X"+str(a)+str(i))
#symbols.add("~X"+str(b)+str(i))
list_clauses.append(clause)
def remove(symbols,P):
temp = set()
if P[0] == "~":
symbols.discard(P[1:])
else:
symbols.discard(P)
for s in symbols:
if s[0:3] == P[0:3]:
temp.add(s)
for i in temp:
symbols.discard(i)
def Union(model,P,type):
if type:
model.add(P)
else:
model.add("~"+P)
return copy.deepcopy(model)
def Answer(model):
global guests
global file_logs
for i in xrange(guests):
for j in model:
element = str(j).split("-")
if element[0] == "X" and element[1] == str(i+1):
file_logs += "\n" + element[1] + " " + element[2]
def ModelCheck(clauses, model):
#clauses = deepcopy(old_clause)
if not model:
return "None"
remove_clauses = []
for mod_element in model:
for clause_element in clauses:
if not clause_element:
return False
if mod_element in clause_element:
remove_clauses.append(clause_element)
#clauses.remove(clause_element)
else:
if mod_element[0] == "~":
if mod_element[1:] in clause_element:
clause_element.remove(mod_element[1:])
else:
if ("~" + mod_element) in clause_element:
clause_element.remove("~" + mod_element)
if not clause_element:
return False
if not clauses:
Answer(model)
return True
for clause_ele in clauses:
if not clause_ele:
return False
for clause in remove_clauses:
clauses.remove(clause)
return "Cont"
def PureSymbol(symbols,clauses,model):
pure_symbol = 0
remove_clauses = []
if not symbols:
return None
for clause_element in clauses:
pure_symbol = 1
for del_clause in clause_element:
for element in clauses:
if del_clause[0] == "~":
if del_clause[1:] in element:
pure_symbol = 0
break
else:
if ("~" + del_clause) in element:
pure_symbol = 0
break
if pure_symbol:
for items in clauses:
if del_clause in items:
remove_clauses.append(items)
for element in remove_clauses:
clauses.remove(element)
return del_clause
return None
def UnitClause(clauses,model):
remove_clauses = []
for clause_element in clauses:
if len(clause_element) == 1:
model.add(clause_element[0])
for del_clause in clauses:
if clause_element[0] in del_clause:
remove_clauses.append(del_clause)
else:
if clause_element[0][0] == "~":
if clause_element[0][1:] in del_clause:
del_clause.remove(clause_element[0][1:])
else:
if ("~" + clause_element[0]) in del_clause:
del_clause.remove("~" + clause_element[0])
for item in remove_clauses:
clauses.remove(item)
return clause_element[0]
return None
def Dpll(clauses,symbols,model):
if not clauses:
Answer(model)
return True
result = ModelCheck(clauses,model)
if result == True:
Answer(model)
return True
elif result == False:
return False
else:
P = PureSymbol(symbols,clauses,model)
if P:
model.add(str(P))
if symbols:
remove(symbols,P)
return Dpll(clauses, symbols, model)
P = UnitClause(clauses,model)
if P:
model.add(str(P))
if symbols:
remove(symbols,P)
return Dpll(clauses, symbols, model)
if not symbols:
Answer(model)
return True
if not clauses:
Answer(model)
return True
P = symbols.pop()
remove(symbols,P)
return Dpll(clauses,copy.deepcopy(symbols),Union(model,P,True)) or \
Dpll(clauses,copy.deepcopy(symbols),Union(model,P,False))
def DpllSatisfiable():
list_symbols = symbols
model = set()
result = Dpll(list_clauses,list_symbols,model)
if result:
print "yes"
output.write("yes\n")
else:
output.write("no\n")
print "no"
print file_logs[1:]
output.write(file_logs[1:])
guests,tables = [int(x) for x in input.readline().strip().split(" ")]
for line in input.readlines():
temp = line.strip().split(" ")
if temp[2] == 'F':
friends.append([temp[0],temp[1]])
else:
enemies.append([temp[0], temp[1]])
Cond1()
Cond2()
Cond3()
DpllSatisfiable()