exercism/rust/bowling/README.md

Bowling

Score a bowling game.

Bowling is a game where players roll a heavy ball to knock down pins arranged in a triangle. Write code to keep track of the score of a game of bowling.

Scoring Bowling

The game consists of 10 frames. A frame is composed of one or two ball throws with 10 pins standing at frame initialization. There are three cases for the tabulation of a frame.

• An open frame is where a score of less than 10 is recorded for the frame. In this case the score for the frame is the number of pins knocked down.

• A spare is where all ten pins are knocked down by the second throw. The total value of a spare is 10 plus the number of pins knocked down in their next throw.

• A strike is where all ten pins are knocked down by the first throw. The total value of a strike is 10 plus the number of pins knocked down in the next two throws. If a strike is immediately followed by a second strike, then the value of the first strike cannot be determined until the ball is thrown one more time.

Here is a three frame example:

Frame 1	Frame 2	Frame 3
X (strike)	5/ (spare)	9 0 (open frame)

Frame 1 is (10 + 5 + 5) = 20

Frame 2 is (5 + 5 + 9) = 19

Frame 3 is (9 + 0) = 9

This means the current running total is 48.

The tenth frame in the game is a special case. If someone throws a strike or a spare then they get a fill ball. Fill balls exist to calculate the total of the 10th frame. Scoring a strike or spare on the fill ball does not give the player more fill balls. The total value of the 10th frame is the total number of pins knocked down.

For a tenth frame of X1/ (strike and a spare), the total value is 20.

For a tenth frame of XXX (three strikes), the total value is 30.

Requirements

Write code to keep track of the score of a game of bowling. It should support two operations:

• roll(pins : int) is called each time the player rolls a ball. The argument is the number of pins knocked down.
• score() : int is called only at the very end of the game. It returns the total score for that game.

Rust Installation

Refer to the exercism help page for Rust installation and learning resources.

Writing the Code

Execute the tests with:

$ cargo test

All but the first test have been ignored. After you get the first test to pass, open the tests source file which is located in the tests directory and remove the #[ignore] flag from the next test and get the tests to pass again. Each separate test is a function with #[test] flag above it. Continue, until you pass every test.

If you wish to run all ignored tests without editing the tests source file, use:

$ cargo test -- --ignored

To run a specific test, for example some_test, you can use:

$ cargo test some_test

If the specific test is ignored use:

$ cargo test some_test -- --ignored

To learn more about Rust tests refer to the online test documentation

Make sure to read the Modules chapter if you haven't already, it will help you with organizing your files.

Further improvements

After you have solved the exercise, please consider using the additional utilities, described in the installation guide, to further refine your final solution.

To format your solution, inside the solution directory use

cargo fmt

To see, if your solution contains some common ineffective use cases, inside the solution directory use

cargo clippy --all-targets

Submitting the solution

Generally you should submit all files in which you implemented your solution (src/lib.rs in most cases). If you are using any external crates, please consider submitting the Cargo.toml file. This will make the review process faster and clearer.

Feedback, Issues, Pull Requests

The exercism/rust repository on GitHub is the home for all of the Rust exercises. If you have feedback about an exercise, or want to help implement new exercises, head over there and create an issue. Members of the rust track team are happy to help!

If you want to know more about Exercism, take a look at the contribution guide.

Source

The Bowling Game Kata at but UncleBob http://butunclebob.com/ArticleS.UncleBob.TheBowlingGameKata

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.