def odv_forward_mrv_mcv_lcv(row, col, domains, board, assignment):
max_count = 0
max_index = 0
domain = domains[str([row, col])]
dictionary = {}
for i in range(len(domain)):
val = domain[i]
count = 0
# row checking
for r in range(board.BoardSize):
if (not sudoku.is_assigned(r, col, board, assignment)) and domains[str([r, col])].count(val):
count += 1
# column checking
for c in range(board.BoardSize):
if (not sudoku.is_assigned(row, c, board, assignment)) and domains[str([row, c])].count(val):
count += 1
# subsquare checking
subsquare = int(math.sqrt(board.BoardSize))
squareRow = row // subsquare
squareCol = col // subsquare
for r in range(subsquare):
for c in range(subsquare):
if (
not sudoku.is_assigned(squareRow * subsquare + r, squareCol * subsquare + c, board, assignment)
) and domains[str([squareRow * subsquare + r, squareCol * subsquare + c])].count(val):
count += 1
dictionary[val] = count
sorted_dictionary = sorted(dictionary.iteritems(), key=operator.itemgetter(1))
dom = []
for dom_val in sorted_dictionary:
dom.append(dom_val[0])
return reversed(dom)
def backtrack_forward_mrv(assignment, board, domains,variable_assignment_count):
variable_assignment_count[0] = variable_assignment_count[0] + 1
# Tests for completion by adding assignments to board, then restores if not
# print " -------------------------"
for i in range(len(assignment)):
board.CurrentGameboard[assignment[i][0]][assignment[i][1]] = assignment[i][2]
# board.print_board()
if sudoku.iscomplete(board.CurrentGameboard):
return assignment
for i in range(len(assignment)):
board.CurrentGameboard[assignment[i][0]][assignment[i][1]] = 0
# Selects the variable to try values for
row, col = select_unassigned_variable_mrv(board,assignment, domains)
# Tries each possible value in the variable's domain
for val in sudoku.odv_forward(row,col,domains):
if sudoku.consistent(assignment, row, col, val,board.BoardSize): # If that value works, adds it to the assignment
assignment.append([row,col,val])
domains, changes, possible = sudoku.forward_check(row,col,val,domains,board,assignment) # Also, restricts the domain of other variables
if possible: # If no conflict is immediately detected, continues to the next variable to be assigned
result = backtrack_forward_mrv(assignment,board,domains, variable_assignment_count)
if result != None: # If that was successful, return its result
return result
if assignment: # Otherwise, remove the assignment and restore the domains
assignment.pop()
domains = sudoku.reverse_forward(changes,domains)
return None # If none of them work, return none
def select_unassigned_variable_mrv(board,assignment,domains):
min_row = 0
min_col = 0
min_len = len(board.CurrentGameboard) + 1
constraining_val = 0
mrv = []
for r in range(board.BoardSize):
for c in range(board.BoardSize):
if not sudoku.is_assigned(r,c,board,assignment):
key = str([r, c])
if len(domains[key]) < min_len:
# val = constraining_value(r, c, board, assignment)
# if(val >= constraining_val):
min_len = len(domains[key])
min_row = r
min_col = c
# constraining_val = val
elif len(domains[key]) == min_len:
val = constraining_value(r, c, board, assignment)
if(val > constraining_val):
min_len = len(domains[key])
min_row = r
min_col = c
constraining_val = val
return min_row, min_col
def backtrack(assignment, board, variable_assignment_count): variable_assignment_count[0] = variable_assignment_count[0] + 1 for i in range(len(assignment)): board.CurrentGameboard[assignment[i][0]][assignment[i][1]] = assignment[i][2] if sudoku.iscomplete(board.CurrentGameboard): return assignment for i in range(len(assignment)): board.CurrentGameboard[assignment[i][0]][assignment[i][1]] = 0 row, col = sudoku.select_unassigned_variable(board,assignment) for val in order_domain_values(row, col, assignment, board): if sudoku.consistent(assignment, row, col, val,board.BoardSize): assignment.append([row,col,val]) result = backtrack(assignment, board, variable_assignment_count) if result != None: return result if assignment: assignment.pop() return None
def constraining_value(row, col, board, assignment):
count = 0;
for i in range(board.BoardSize):
if not sudoku.is_assigned(row, i, board, assignment):
count += 1
if not sudoku.is_assigned(i, col, board, assignment):
count += 1
# print count
subsquare = int(math.sqrt(board.BoardSize))
squareRow = row // subsquare
squareCol = col // subsquare
# return count
for r in range(subsquare):
for c in range(subsquare):
if not sudoku.is_assigned(r, c, board, assignment):
count += 1
# print count
return count
def backtracking_search_forward_checking_mrv(csp):
domains = sudoku.initialize_domains(csp)
return backtrack_forward_mrv([],csp,domains,variable_assignment_count)
return min_row, min_col
def constraining_value(row, col, board, assignment):
count = 0;
for i in range(board.BoardSize):
if not sudoku.is_assigned(row, i, board, assignment):
count += 1
if not sudoku.is_assigned(i, col, board, assignment):
count += 1
# print count
subsquare = int(math.sqrt(board.BoardSize))
squareRow = row // subsquare
squareCol = col // subsquare
# return count
for r in range(subsquare):
for c in range(subsquare):
if not sudoku.is_assigned(r, c, board, assignment):
count += 1
# print count
return count
# Test code for a file with a board
test_board = sudoku.parse_file('test9.txt')
tboard = sudoku.SudokuBoard(len(test_board),test_board)
tboard.print_board()
backtracking_search_forward_checking_mrv(tboard)
tboard.print_board()
print variable_assignment_count[0]
# subsquare checking
subsquare = int(math.sqrt(board.BoardSize))
squareRow = row // subsquare
squareCol = col // subsquare
for r in range(subsquare):
for c in range(subsquare):
if (
not sudoku.is_assigned(squareRow * subsquare + r, squareCol * subsquare + c, board, assignment)
) and domains[str([squareRow * subsquare + r, squareCol * subsquare + c])].count(val):
count += 1
dictionary[val] = count
sorted_dictionary = sorted(dictionary.iteritems(), key=operator.itemgetter(1))
dom = []
for dom_val in sorted_dictionary:
dom.append(dom_val[0])
return reversed(dom)
# Test code for a file with a board
test_board = sudoku.parse_file("test25.txt")
tboard = sudoku.SudokuBoard(len(test_board), test_board)
tboard.print_board()
backtracking_search_forward_checking_mrv_mcv_lcv(tboard)
tboard.print_board()
print variable_assignment_count[0]
def order_domain_values(row,col,assignment,board):
domain_values = []
for x in range(1,board.BoardSize+1):
if sudoku.in_domain(row,col,x,board):
domain_values.append(x)
return domain_values
def select_unassigned_variable(board,assignment):
for r in range(board.BoardSize):
for c in range(board.BoardSize):
if not sudoku.is_assigned(r,c,board,assignment):
return r, c