iterizerjs/spec/project-euler/problem8.js

Expressive & concise code using ES6 iterables

var should = require('chai').should();

describe('Project Euler Problem #8', function() {
	function largestProductInSeries(data, seriesLength) {
		var largestProduct = 0;
	
		for(var startIndex of range(0, data.length - seriesLength)) {
			var nextSeries = data.substr(startIndex, seriesLength);
			var product = nextSeries.chars().map(function(c) {return Number(c)}).product();

			if(product > largestProduct) {
				largestProduct = product;
			}
		}

		return largestProduct;
	}

	var data =
		'73167176531330624919225119674426574742355349194934' +
		'96983520312774506326239578318016984801869478851843' +
		'85861560789112949495459501737958331952853208805511' +
		'12540698747158523863050715693290963295227443043557' +
		'66896648950445244523161731856403098711121722383113' +
		'62229893423380308135336276614282806444486645238749' +
		'30358907296290491560440772390713810515859307960866' +
		'70172427121883998797908792274921901699720888093776' +
		'65727333001053367881220235421809751254540594752243' +
		'52584907711670556013604839586446706324415722155397' +
		'53697817977846174064955149290862569321978468622482' +
		'83972241375657056057490261407972968652414535100474' +
		'82166370484403199890008895243450658541227588666881' +
		'16427171479924442928230863465674813919123162824586' +
		'17866458359124566529476545682848912883142607690042' +
		'24219022671055626321111109370544217506941658960408' +
		'07198403850962455444362981230987879927244284909188' +
		'84580156166097919133875499200524063689912560717606' +
		'05886116467109405077541002256983155200055935729725' +
		'71636269561882670428252483600823257530420752963450';

	it('displays the largest product using four adjacent digits', function() {
		largestProductInSeries(data, 4).should.equal(5832);
	});

	it('displays the largest product using four adjacent digits', function() {
		largestProductInSeries(data, 13).should.equal(23514624000);
	});
});