Class OptionalObjective

An optional objective in an ExactCoverGraph. An optional objective is both an IObjective and an IPossibility.

This can be satisfied if one or more attached IPossibility objects are selected. Once satisfied, this drops any remaining unknown possibilities, and notifies parent objectives that to select this possibility.

Unlike Objectives, this class can be dropped. Dropping this objetive does not immediately impact attached possibilities. These possibilities may still be dropped or selected, as long as this objective does not become satisfied. If selecting a possibility would satisfy a dropped optional objective, then the call to SudokuSpice.ConstraintBased.IObjective.TrySelectPossibility(SudokuSpice.ConstraintBased.Link) will fail.

All OptionalObjective objects must eventually be descendents of at least one Objective.

Inheritance

System.Object

OptionalObjective

Implements

IOptionalObjective

IObjective

IPossibility

Inherited Members

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.ToString()

Namespace: SudokuSpice.ConstraintBased

Assembly: SudokuSpice.dll

Syntax

public sealed class OptionalObjective : IOptionalObjective, IObjective, IPossibility

Properties

IsConcrete

True if this possibility is a concrete possibility, i.e. a leaf node in the graph, as opposed to a group of other possibilities.

Declaration

public bool IsConcrete { get; }

Property Value

Type	Description
System.Boolean

State

The current state of this node in the ExactCoverGraph.

Declaration

public NodeState State { get; }

Property Value

Type	Description
NodeState

Methods

CreateWithPossibilities(ReadOnlySpan<IPossibility>, Int32)

Creates an optional objective with the given possibilities attached. This objective will be satisfied when countToSatisfy of these possibilities are selected.

Note that this results in an OptionalObjective with no parent objectives. The returned objective must eventually be connected to at least one top-level required Objective object in order to behave correctly.

Declaration

public static OptionalObjective CreateWithPossibilities(ReadOnlySpan<IPossibility> possibilities, int countToSatisfy)

Parameters

Type	Name	Description
System.ReadOnlySpan<IPossibility>	possibilities	The possibilities that could satisfy this objective.
System.Int32	countToSatisfy	The number of possibilities that must be selected to satisfy this objective.

Returns

Type	Description
OptionalObjective	The newly constructed optional objective.

Exceptions

Type	Condition
System.ArgumentException	If the countToSatisfy is less than 1 or is impossible with the given number of possibilities.

GetUnknownDirectPossibilities()

Retrieves any possibilities that are direct descendents of this objective and whose states are unknown.

Declaration

public IEnumerable<IPossibility> GetUnknownDirectPossibilities()

Returns

Type	Description
System.Collections.Generic.IEnumerable<IPossibility>

Implements

IOptionalObjective

IObjective

IPossibility