Software engineering - Exercise 3 - N-Queens solver

Installation instructions

Install rust. Instructions can be found here)
Clone this repository
In the repository folder, use the command cargo build --release
Eat some cookies while it compiles (it might take two or three minutes to gather all packages necessary and to compile everything)
To run, you can either launch the program from the target\release folder, or use the command cargo run --release -- [program args]

Options details

Strategy

Each exploration of the solutions space is managed by a strategy. A strategy will partition the solutions space in batches. Each batches consist of (eventually partial) solutions which are all displayed by the driver. When a batch ends, the driver will wait for the user if such interaction is enabled.

AllSteps: Each batch holds the next partial solution.
SolutionsWithSteps: Each batch holds the all partial solutions until a complete solution is found. Thus, all partial solutions will be displayed, and once a complete solution is found, it is displayed and the driver eventually wait for the user.
OnlySolutions: Each batch holds the next complete solution. No partial solution is ever shown.
OnlyCount: The batch is empty, and no solution is displayed. However, the solutions space is still fully explored to count the solutions.

Interaction Mode

NoInteraction: All solutions selected by the strategy option are displayed one after the other
WaitUser: Wait some input from the user to continue the exploration of the solutions space after a batch is finished.
WaitOrTimeout: Not yet implemented. If selected, will behave like WaitUser

Driver

Console: Prints a solution as an array in the console. Each element in position i indicates the position of the i-th queen on the i-th line. When a solution is found, it is indicated. Sample with option --stop-after-first:

Searching for size 7...
[0]
[0, 2]
[0, 2, 4]
[0, 2, 4, 1]
[0, 2, 4, 1, 3]
[0, 2, 4, 6]
[0, 2, 4, 6, 1]
[0, 2, 4, 6, 1, 3]
[0, 2, 4, 6, 1, 3, 5]
Solution found!
Number of solutions found: 1

3D: Displays a 3D scene with a board and the queens.

Usage

You can use --help to get basic information on each option offered.

Solve the N-Queens problem with different modes of interaction and visualisation

USAGE:
    n-queens.exe [FLAGS] [OPTIONS] [size]

FLAGS:
    -h, --help                Prints help information
        --stop-after-first    If enabled, the solver will not output any more steps as soon as a solution is found. Has
                              no effect if the strategy is set to OnlyCount (it will still count all solutions).
    -V, --version             Prints version information

OPTIONS:
        --driver <Driver>                 Select the driver.
                                          'Console' writes in the console.
                                          3D will display a 3D scene to visualise the board.
                                          Default is 'Console'.
                                           [possible values: Console, 3D]
        --interaction <InterationMode>    Select the Interaction Mode. WaitOrTimeout is not yet implemented.
                                          Default is 'WaitUser'.
                                           [possible values: NoInteraction, WaitUser, WaitOrTimeout]
        --strat <Strategy>                Select the strategy. A strategy defines when to stop for the user to interact
                                          and which intermediate steps are shown.
                                          Default is 'SolutionsWithSteps'.
                                           [possible values: AllSteps, SolutionsWithSteps, OnlySolutions, OnlyCount]

ARGS:
    <size>    The size of the board, and so the number of queens. Default is 7

Code organisation

root
├─ resources         contains the resources of this repo, like 3d models, images
└─ src               source code folder
   ├─ drivers        contains the source of each driver
   │  ├─ board_3d    the source folder of the 3d driver
   │  │  └── ...
   │  └─ console.rs  the source for the console driver
   ├─ strategies     contains the source of each strategy
   ├─ driver.rs      defines some types and the requirements a driver must meet
   ├─ main.rs        main program, handles command-line options and dispatches them
   ├─ solver.rs      n-queens solver. The function 'search' gives the next partial
   │                 solution. 'backtrack_once' backtrack only one line.
   │                 The solver was implemented with an iterator approach to have
   │                 more flexibility. Using coroutines would have been ideal but
   │                 the language does not fully support this feature
   └─ strategy.rs    defines the requirements a strategy must meet

Clematrics / n-queens