在谷歌或工具中保持变量出现的计数

我在玩OR Tools,只是想知道是否有任何方法可以保持某个约束满足的次数?

在这种情况下,我想记录我的“diff”变量为-1、-2、0、2等的次数。

我已经从官方文档中获得了解决方案打印机,所以我是否也必须以任何方式编辑/调整它才能返回计数?

提前谢谢,我是新手。

from ortools.sat.python import cp_model
model = cp_model.CpModel()
x = model.NewIntVar(0, 10, 'x')
y = model.NewIntVar(0, 10, 'y')
diff = model.NewIntVar(-10,10,'diff')
model.Add(diff == x - y)
#occurences of each diff

#solution printer
class VarArraySolutionPrinter(cp_model.CpSolverSolutionCallback):
    """Print intermediate solutions."""

    def __init__(self, variables):
        cp_model.CpSolverSolutionCallback.__init__(self)
        self.__variables = variables
        self.__solution_count = 0

    def on_solution_callback(self):
        self.__solution_count += 1
        for v in self.__variables:
            print(f"{v}={self.Value(v)}", end=" ")
        print()

    def solution_count(self):
        return self.__solution_count

solver = cp_model.CpSolver()
# solver.parameters.log_search_progress = True
solution_printer = VarArraySolutionPrinter([x, y, diff])
solver.parameters.enumerate_all_solutions = True
status = solver.Solve(model, solution_printer)