def solve(self):
"""
Searches for a solution using a combination of arcConsistency
and backtracking. The Algorithm will run arcConsistency,
find the smallest remaining domain (that's greater than 1), and
systematically assign a value to the variable and recurse onwards.
Returns True if a solution is found, False otherwise.
"""
self.arcConsistencyHelper()
if self.isSolved():
for coordinate in self.board.getCoordinates():
coordinate.setValue(coordinate.getDomain()[0])
return True
elif self.isDeadEnd():
return False
else:
print("selecting a variable to assign")
savedDomains = self.backupDomains(self.getListOfDomains())
smallest = self.indexOfSmallestDomain(savedDomains)
for x in savedDomains[smallest]:
self.addRelatedToQueue(self.coordinates[smallest])
self.coordinates[smallest].setDomain([x,])
if (self.solve()):
return True
self.restoreDomains(self.backupDomains(savedDomains))
else:
return False
def solve(self):
"""
Searches for a solution using a combination of arcConsistency
and backtracking. The Algorithm will run arcConsistency,
find the smallest remaining domain (that's greater than 1), and
systematically assign a value to the variable and recurse onwards.
Returns True is a solution is found, False otherwise.
"""
self.arcConsistencyHelper()
if self.isSolved():
for coordinate in self.board.getCoordinates():
coordinate.setValue(coordinate.getDomain()[0])
return True
elif self.isDeadEnd():
return False
else:
print("selecting a variable to assign")
savedDomains = self.backupDomains(self.getListOfDomains())
smallest = self.indexOfSmallestDomain(savedDomains)
for x in savedDomains[smallest]:
self.addRelatedToQueue(self.coordinates[smallest])
self.coordinates[smallest].setDomain([
x,
])
if (self.solve()):
return True
self.restoreDomains(self.backupDomains(savedDomains))
else:
return False
def solveWithLCV(self):
"""
Works the same as solveWithBackTracking, but assigns the variable
in an order such that you assign the least constraining value first.
That is, assign the value which would cause the least domain pruning
after running arcConsistency.
"""
self.arcConsistencyHelper()
if self.isSolved():
for coordinate in self.board.getCoordinates():
coordinate.setValue(coordinate.getDomain()[0])
return True
elif self.isDeadEnd():
return False
else:
savedDomains = self.backupDomains(self.getListOfDomains())
smallest = self.indexOfSmallestDomain(savedDomains)
resultingDomainsList = []
for x in savedDomains[smallest]:
self.addRelatedToQueue(self.coordinates[smallest])
self.coordinates[smallest].setDomain([
x,
])
self.arcConsistencyHelper()
resultingDomainsList.append((x, self.getListOfDomains()))
self.restoreDomains(self.backupDomains(savedDomains))
for assignment, resultingDomains in resultingDomainsList:
for domain in resultingDomains:
if (len(domain) == 0):
resultingDomainsList.remove(
(assignment,
resultingDomains)) #This assignment cannot work
break
#compute resulting total domain sizes
mappedTotalDomainSizes = list(
map(self.totalSizeOfDomains,
[domains for assignment, domains in resultingDomainsList]))
#pick the assigned variables, ordered by resulting domain size
for i in range(len(resultingDomainsList)):
currentAssignmentIndex = mappedTotalDomainSizes.index(
max(mappedTotalDomainSizes))
currentAssignment, currentDomains = resultingDomainsList[
currentAssignmentIndex]
self.restoreDomains(currentDomains)
self.coordinates[smallest].setDomain([
currentAssignment,
])
if (self.solveWithLCV()):
return True
else:
return False
def solveWithLCV(self):
"""
Works the same as solveWithBackTracking, but assigns the variable
in an order such that you assign the least constraining value first.
That is, assign the value which would cause the least domain pruning
after running arcConsistency.
"""
self.arcConsistencyHelper()
if self.isSolved():
for coordinate in self.board.getCoordinates():
coordinate.setValue(coordinate.getDomain()[0])
return True
elif self.isDeadEnd():
return False
else:
savedDomains = self.backupDomains(self.getListOfDomains())
smallest = self.indexOfSmallestDomain(savedDomains)
resultingDomainsList = []
for x in savedDomains[smallest]:
self.addRelatedToQueue(self.coordinates[smallest])
self.coordinates[smallest].setDomain([x,])
self.arcConsistencyHelper()
resultingDomainsList.append((x, self.getListOfDomains()))
self.restoreDomains(self.backupDomains(savedDomains))
for assignment, resultingDomains in resultingDomainsList:
for domain in resultingDomains:
if (len(domain) == 0):
resultingDomainsList.remove((assignment, resultingDomains)) #This assignment cannot work
break
#compute resulting total domain sizes
mappedTotalDomainSizes = list(map(self.totalSizeOfDomains,
[domains for assignment, domains in resultingDomainsList]))
#pick the assigned variables, ordered by resulting domain size
for i in range(len(resultingDomainsList)):
currentAssignmentIndex = mappedTotalDomainSizes.index(max(mappedTotalDomainSizes))
currentAssignment, currentDomains = resultingDomainsList[currentAssignmentIndex]
self.restoreDomains(currentDomains)
self.coordinates[smallest].setDomain([currentAssignment,])
if (self.solveWithLCV()):
return True
else:
return False
