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brunnock's solution

to Series in the JavaScript Track

Published at Jul 13 2018 · 0 comments
Instructions
Test suite
Solution

Note:

This solution was written on an old version of Exercism. The tests below might not correspond to the solution code, and the exercise may have changed since this code was written.

Given a string of digits, output all the contiguous substrings of length n in that string.

For example, the string "49142" has the following 3-digit series:

  • 491
  • 914
  • 142

And the following 4-digit series:

  • 4914
  • 9142

And if you ask for a 6-digit series from a 5-digit string, you deserve whatever you get.

Note that these series are only required to occupy adjacent positions in the input; the digits need not be numerically consecutive.

Setup

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

http://exercism.io/languages/javascript/installation

Running the test suite

The provided test suite uses Jasmine. You can install it by opening a terminal window and running the following command:

npm install -g jasmine

Run the test suite from the exercise directory with:

jasmine series.spec.js

In many test suites all but the first test have been marked "pending". Once you get a test passing, activate the next one by changing xit to it.

Source

A subset of the Problem 8 at Project Euler http://projecteuler.net/problem=8

Submitting Incomplete Solutions

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

series.spec.js

var Series = require('./series');

describe('Series', function () {
  it('has digits (short)', function () {
    expect(new Series('01234').digits).toEqual([0, 1, 2, 3, 4]);
  });

  xit('has digits (long)', function () {
    expect(new Series('0123456789').digits)
      .toEqual([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
  });

  xit('keeps the digit order if reversed', function () {
    expect(new Series('9876543210').digits)
      .toEqual([9, 8, 7, 6, 5, 4, 3, 2, 1, 0]);
  });

  xit('keeps arbitrary digit order', function () {
    expect(new Series('936923468').digits)
      .toEqual([9, 3, 6, 9, 2, 3, 4, 6, 8]);
  });

  xit('can slice by 1', function () {
    expect(new Series('01234').slices(1))
      .toEqual([[0], [1], [2], [3], [4]]);
  });

  xit('can slice by 2', function () {
    expect(new Series('98273463').slices(2))
      .toEqual([[9, 8], [8, 2], [2, 7], [7, 3], [3, 4], [4, 6], [6, 3]]);
  });

  xit('can slice by 3', function () {
    expect(new Series('01234').slices(3))
      .toEqual([[0, 1, 2], [1, 2, 3], [2, 3, 4]]);
  });

  xit('can slice by 3 with duplicate digits', function () {
    expect(new Series('31001').slices(3))
      .toEqual([[3, 1, 0], [1, 0, 0], [0, 0, 1]]);
  });

  xit('can slice by 4', function () {
    expect(new Series('91274').slices(4))
      .toEqual([[9, 1, 2, 7], [1, 2, 7, 4]]);
  });

  xit('can slice by 5', function () {
    expect(new Series('81228').slices(5))
      .toEqual([[8, 1, 2, 2, 8]]);
  });

  xit('throws an error if not enough digits to slice', function () {
    expect( function () {
      new Series('01032987583').slices(12);
    }).toThrow(new Error('Slice size is too big.'));
  });
});
function Series(num){

    this.digits = num.split('').map(function(x){return +x});

    this.slices = function(size){
	if (size > this.digits.length) throw 'Slice size is too big.';
	var slices=[];
	for (var x=0; x<this.digits.length-size+1; ++x) {
	    slices.push(this.digits.slice(x,x+size));
	} 
	return slices;
    }
}

module.exports=Series;

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