添加约束时Microsoft Solver Foundation引发ArgumentNullException

Question

我正在尝试为呼叫中心制定一个时间表，我试图在高呼叫时段最大化员工，并在低时段最小化。为简单起见，它看起来像：

我有以下代码：

var startTimes = BuildStartTimes();
var employees = BuildEmployees();
ConstraintSystem solver = ConstraintSystem.CreateSolver();
CspDomain wrkTime = solver.CreateIntegerSet(startTimes);
CspTerm[][] scheduleMatrix = solver.CreateVariableArray(wrkTime, "Schedule", employees.Length, startTimes.Length);

//iterate through times adding column constraints
for (int i = 0; i < startTimes.Length -1; i++)
{
    //add constraint for employees numbers
    for (int emp = 0; emp < employees.Length; emp++)
    {
        //for simplistic sake, the Ids i to 9 represent employee Ids
        scheduleMatrix[emp][i].Model.CreateIntegerSet(new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 }); 
    }

    solver.AddConstraints(
            //add constraint that the employee can be added just once
            solver.GreaterEqual(NumberOfWorkersRequiredForShift(i, employees), GetColumn(scheduleMatrix, i)),
            //employee can only list once
            solver.Unequal(GetColumn(scheduleMatrix,i))
        );
}

for (int i = 0; i < employees.Length -1; i++)
{
    solver.AddConstraints(
            //employee can only listed nine consecutive 36 times maximum 
            //4 * 15 minutes * 9 hours == 4 * 9 == 36
            solver.Equal(36,GetRow(scheduleMatrix,i))
        );
}

private static CspTerm[] GetColumn(CspTerm[][] matrix, int column)
{

    CspTerm[] slice = new CspTerm[matrix.Length];
    for (int row = 0; row < matrix.Length; row++)
        slice[row] = matrix[row][column];

    return slice;
}

private static CspTerm[] GetRow(CspTerm[][] matrix, int row)
{
    CspTerm[] slice = new CspTerm[matrix[0].Length];
    for (int col = 0; col < matrix.Length; col++)
        slice[col] = matrix[row][col];

    return slice;
}

我在将雇员限制为9小时（例如4个15分钟* 9小时= 36次）的约束下得到ArgumentNullException。

这是堆栈跟踪：

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在   Microsoft.SolverFoundation.Solvers.ConstraintSystem.ValidateInputs（CspTerm []   输入）   Microsoft.SolverFoundation.Solvers.ConstraintSystem.Equal（的Int32   CSPCallCenterDemo.Program.Main（String []中的常量，CspTerm []输入）   args）在c：\ Users \ wdniels \ Documents \ Visual Studio中   2012 \ Projects \ CSPCallCenterDemo \ CSPCallCenterDemo \ Program.cs：第40行   在System.AppDomain._nExecuteAssembly（RuntimeAssembly程序集，   System.AppDomain.ExecuteAssembly上的String [] args）（String   assemblyFile，Evidence assemblySecurity，String [] args）at   Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly（）at   System.Threading.ThreadHelper.ThreadStart_Context（Object state）at   System.Threading.ExecutionContext.RunInternal（执行上下文   executionContext，ContextCallback回调，对象状态，布尔值   preserveSyncCtx）at   System.Threading.ExecutionContext.Run（执行上下文   executionContext，ContextCallback回调，对象状态，布尔值   preserveSyncCtx）at   System.Threading.ExecutionContext.Run（执行上下文   executionContext，ContextCallback回调，对象状态）at   System.Threading.ThreadHelper.ThreadStart（）

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也有人知道如何添加一个约束来确保员工连续工作36 <连续 15分钟？

Answer 1

你得到ArgumentException，因为GetRow代码没有完全填充CspTerm。 你必须像这样重写它：

    private static CspTerm[] GetRow(CspTerm[][] matrix, int row)
    {
        CspTerm[] slice = new CspTerm[matrix[0].Length];
        for (int col = 0; col < matrix[0].Length; col++)
            slice[col] = matrix[row][col];

        return slice;
    }