Comp211 HW11 Supporting Code Details
Core Data Structures
The main data structures are represented by only a few interfaces:
ICell
-- a single square on the Sudoku board.- A cell has a set of integer values, which are accessible either as a
HashSet<Integer>
- A cell also has a collection (Vector<ICell>) of
ICellSets
to which it belongs. These are the cell's row, column and block, in that order.- Don't forget that the cell is also a member of every ICellSet that it references.
- A cell can be in one of three logical states:
- Empty - there are no values contained in the cell. This corresponds to the situation where the board is unsolvable because a cell has no possible value.
Solved - the cell contains exactly one value. If and only if you know for sure that the cell is in this state, then the single value can be accessed as
aCell.getValueArray()[0]
.- Unsolved - the cell contains multiple possible values. At most, a cell could contain
order*order
values.
Cell
is a concrete implementation ofICell
.- An
ICell
accepts anICellVisitor
which has cases for each of the 3 logical states, described above.- The
ACellVisitor
class is an abstract convenience class that provide a default return value for any cases that the developer does not which to override. There is no requirement to use this class, though it may simplify certain code.
- The
- A cell has a set of integer values, which are accessible either as a
ICellSet
-- A collection ofICells
that represents a row, column or block.- For convenience sake, the cells are in a distinct order (i.e. left-to right for a row) and thus each cell is addressable by an index value.
- An
ICellSet
isIterable
which means that it can be used in for-each loops, e.g.for(ICell c : aCellSet) { ... }
Board
-- A set of 3 Vector<ICellSet>'s where each element of the vector is anICellSet
. These vectors represent the entire set of rows, columns or blocks in a game.- A
Board
has the ability to make a "deep" copy of itself, where everything, all the way down to the individual cells, is copied. This is theclone()
method. - The
Board
also has a utility method for generating empty cell sets, which is used during initialization. - It should be noted that since every cell appears exactly once in each of the
rows
,cols
, andblks
Vectors
of aBoard
, any of those 3 vectors will server equally well as a means to iterate over all the cells of aBoard
- A
Utility Data Structures Delegation-model programming and imperative (conditional and loop-based) programming have a fundamental incompatibility: Delegation works by having code on the inside of an object (i.e. a method of that object) perform the object-specific processes. On the other hand, imperative programming utilizes program structures (conditionals and loops) which are outside the object to perform object-specific processes. This can cause major architectural headaches when combining both styles in a program, which is what we are doing here. For instance, see the programming hints section on the previous wiki page on how to control loops and mutate data while in the middle of a delegation process.The following utility data structures are designed to handle the situation where an operation has more than 2 or more possible outcomes.
Model-View-Controller Architecture
Puzzle Generation Utilities