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to Scrabble Score in the TypeScript Track

Published at May 20 2020 · 0 comments
Instructions
Test suite
Solution

Given a word, compute the scrabble score for that word.

Letter Values

You'll need these:

Letter                           Value
A, E, I, O, U, L, N, R, S, T       1
D, G                               2
B, C, M, P                         3
F, H, V, W, Y                      4
K                                  5
J, X                               8
Q, Z                               10

Examples

"cabbage" should be scored as worth 14 points:

  • 3 points for C
  • 1 point for A, twice
  • 3 points for B, twice
  • 2 points for G
  • 1 point for E

And to total:

  • 3 + 2*1 + 2*3 + 2 + 1
  • = 3 + 2 + 6 + 3
  • = 5 + 9
  • = 14

Extensions

  • You can play a double or a triple letter.
  • You can play a double or a triple word.

Setup

Go through the setup instructions for TypeScript to install the necessary dependencies:

https://exercism.io/tracks/typescript/installation

Requirements

Install assignment dependencies:

$ yarn install

Making the test suite pass

Execute the tests with:

$ yarn test

In the test suites all tests but the first have been skipped.

Once you get a test passing, you can enable the next one by changing xit to it.

Source

Inspired by the Extreme Startup game https://github.com/rchatley/extreme_startup

Submitting Incomplete Solutions

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

scrabble-score.test.ts

import score from './scrabble-score'

describe('Scrabble', () => {
  it('scores an empty word as zero', () => expect(score('')).toEqual(0))

  xit('scores a null as zero', () => expect(score(undefined)).toEqual(0))

  xit('scores a very short word', () => expect(score('a')).toEqual(1))

  xit('scores the word by the number of letters', () => expect(score('street')).toEqual(6))

  xit('scores more complicated words with more', () => expect(score('quirky')).toEqual(22))

  xit('scores case insensitive words', () => expect(score('OXYPHENBUTAZONE')).toEqual(41))

})
const POINTS: { [key: string]: number } = {
  A: 1, E: 1, I: 1, O: 1, U: 1, L: 1, N: 1, R: 1, S: 1, T: 1,
  D: 2, G: 2,
  B: 3, C: 3, M: 3, P: 3,
  F: 4, H: 4, V: 4, W: 4, Y: 4,
  K: 5,
  J: 8, X: 8,
  Q: 10, Z: 10,
};
const LETTER_BONUS = /\w\**/g;
const WORD_BONUS = /!/g;

function readTilePoints(tile: string) {
  const [letter, bonus] = tile.match(/\w|\*+/g) ?? [];
  return POINTS[letter] * (bonus?.length || 1);
}

function score(word: string | undefined) {
  if (!word) return 0;

  const wordBonus = word.match(WORD_BONUS)?.length ?? 1;
  const tiles = word.toUpperCase().match(LETTER_BONUS) ?? [];

  let score = 0;
  for (const tile of tiles) {
    score += readTilePoints(tile);
  }

  return score * wordBonus;
}

export default score;

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