Question

我正在尝试找出如何从ortools.sat.python.cp_model获取可能的解决方案的完整列表。我知道我可以打印它们，如下面的示例所示，但是我不清楚如何获取值，例如作为嵌套列表或字典列表。我尝试通过修改VarArraySolutionPrinter并将自己的解决方案附加到list属性来编写自己的回调类，但是由于某些原因，这始终导致python内核崩溃。无论如何，必须有更直接的方法。我不考虑解析打印输出。

from ortools.sat.python import cp_model

model = cp_model.CpModel()

x00 = model.NewBoolVar('x00')
x01 = model.NewBoolVar('x01')
x02 = model.NewBoolVar('x02')

model.AddBoolOr([x00, x01, x02.Not()])
model.AddBoolOr([x00.Not(), x02.Not()])

# Create a solver and solve.
solver = cp_model.CpSolver()
solution_printer = cp_model.VarArraySolutionPrinter([x00, x01, x02])
solver.SearchForAllSolutions(model, solution_printer)

## Prints:
Solution 0, time = 0.00 s
  x00 = 0   x01 = 1   x02 = 0 
Solution 1, time = 0.01 s
  x00 = 0   x01 = 0   x02 = 0 
Solution 2, time = 0.01 s
  x00 = 0   x01 = 1   x02 = 1 
Solution 3, time = 0.01 s
  x00 = 1   x01 = 1   x02 = 0 
Solution 4, time = 0.01 s
  x00 = 1   x01 = 0   x02 = 0

Answer 1

结果证明编写自定义回调类毕竟可行：

from ortools.sat.python import cp_model

model = cp_model.CpModel()

x00 = model.NewBoolVar('x00')
x01 = model.NewBoolVar('x01')
x02 = model.NewBoolVar('x02')

model.AddBoolOr([x00, x01, x02.Not()])
model.AddBoolOr([x00.Not(), x02.Not()])

class VarArraySolutionCollector(cp_model.CpSolverSolutionCallback):

    def __init__(self, variables):
        cp_model.CpSolverSolutionCallback.__init__(self)
        self.__variables = variables
        self.solution_list = []

    def on_solution_callback(self):
        self.solution_list.append([self.Value(v) for v in self.__variables])

# Create a solver and solve.
solver = cp_model.CpSolver()
solution_collector = VarArraySolutionCollector([x00, x01, x02])
solver.SearchForAllSolutions(model, solution_collector)

solution_collector.solution_list

Out[33]: [[0, 1, 0], [0, 0, 0], [0, 1, 1], [1, 1, 0], [1, 0, 0]]

从ortools获取SAT解决方案列表

1 个答案: