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Merge pull request #90 from ErikSchierboom/largest-series-product
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Update largest-series-product exercise. Fixes #64
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@ErikSchierboom
ErikSchierboom authored Aug 31, 2016
2 parents b6c05c0 + d54983f commit e609512
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Showing 2 changed files with 176 additions and 48 deletions.
44 changes: 18 additions & 26 deletions exercises/largest-series-product/Example.cs
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Expand Up @@ -2,41 +2,33 @@
using System.Collections.Generic;
using System.Linq;

public class LargestSeriesProduct
public static class LargestSeriesProduct
{
private readonly string digits;
public static long GetLargestProduct(string digits, int span) => GetSlices(ParseDigits(digits), span).Max(l => GetProduct(l));

private int[] Digits;

public LargestSeriesProduct(string digits)
private static IEnumerable<IEnumerable<long>> GetSlices(long[] digits, int span)
{
this.digits = digits;
Digits = ParseValues(digits);
}
if (span < 0 || span > digits.Length)
{
throw new ArgumentException("Invalid span.");
}

private int[] ParseValues(IEnumerable<char> values)
{
return values.Select(x => int.Parse(x.ToString())).ToArray();
return Enumerable.Range(0, GetNumberOfSlices(digits, span)).Select(i => digits.Skip(i).Take(span));
}

private int[][] GetSlices(int limit)
private static long[] ParseDigits(string digits) => digits.ToCharArray().Select(ParseDigit).ToArray();

private static long ParseDigit(char c)
{
if (limit > digits.Length) throw new ArgumentException("Slice size is too big");
var slices = new List<int[]>();
for (int i = 0; i <= digits.Length - limit; i++)
if (!char.IsDigit(c))
{
slices.Add(ParseValues(digits.Skip(i).Take(limit)));
throw new ArgumentException("Invalid digit.");
}
return slices.ToArray();
}

public int GetLargestProduct(int seriesLength)
{
if (seriesLength < 1) return 1;
return GetSlices(seriesLength).Aggregate(0, (prev, next) =>
{
int product = next.Aggregate((x, y) => x * y);
return product > prev ? product : prev;
});
return long.Parse(c.ToString());
}

private static long GetProduct(IEnumerable<long> numbers) => numbers.Aggregate(1L, (x, product) => x * product);

private static int GetNumberOfSlices(long[] digits, int span) => digits.Length + 1 - span;
}
180 changes: 158 additions & 22 deletions exercises/largest-series-product/LargestSeriesProductTest.cs
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Expand Up @@ -4,49 +4,185 @@
[TestFixture]
public class LargestSeriesProductTest
{
[TestCase("01234567890", 2, ExpectedResult = 72)]
[TestCase("1027839564", 3, ExpectedResult = 270)]
public int Gets_the_largest_product(string digits, int seriesLength)
[Test]
public void Can_find_the_largest_product_of_2_with_numbers_in_order()
{
const string digits = "0123456789";
const int span = 2;
const int expected = 72;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Can_find_the_largest_product_of_2()
{
const string digits = "576802143";
const int span = 2;
const int expected = 48;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Finds_the_largest_product_if_span_equals_length()
{
const string digits = "29";
const int span = 2;
const int expected = 18;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Can_find_the_largest_product_of_3_with_numbers_in_order()
{
const string digits = "0123456789";
const int span = 3;
const int expected = 504;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Can_find_the_largest_product_of_3()
{
const string digits = "1027839564";
const int span = 3;
const int expected = 270;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Can_find_the_largest_product_of_5_with_numbers_in_order()
{
const string digits = "0123456789";
const int span = 5;
const int expected = 15120;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Can_get_the_largest_product_of_a_big_number()
{
const string digits = "73167176531330624919225119674426574742355349194934";
const int span = 6;
const int expected = 23520;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Can_get_the_largest_product_of_a_big_number_II()
{
const string digits = "52677741234314237566414902593461595376319419139427";
const int span = 6;
const int expected = 28350;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Can_get_the_largest_product_of_a_big_number_III()
{
const string digits = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450";
const int span = 13;
const long expected = 23514624000;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Reports_zero_if_the_only_digits_are_zero()
{
const string digits = "0000";
const int span = 2;
const int expected = 0;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Reports_zero_if_all_spans_include_zero()
{
return new LargestSeriesProduct(digits).GetLargestProduct(seriesLength);
const string digits = "99099";
const int span = 3;
const int expected = 0;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Largest_product_works_for_small_numbers()
public void Reports_1_for_empty_string_and_empty_product_0_span()
{
Assert.That(new LargestSeriesProduct("19").GetLargestProduct(2), Is.EqualTo(9));
const string digits = "";
const int span = 0;
const int expected = 1;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[Test]
public void Largest_product_works_for_large_numbers()
public void Reports_1_for_nonempty_string_and_empty_product_0_span()
{
const string LARGE_NUMBER = "73167176531330624919225119674426574742355349194934";
Assert.That(new LargestSeriesProduct(LARGE_NUMBER).GetLargestProduct(6), Is.EqualTo(23520));
const string digits = "123";
const int span = 0;
const int expected = 1;

Assert.That(LargestSeriesProduct.GetLargestProduct(digits, span), Is.EqualTo(expected));
}

[Ignore("Remove to run test")]
[TestCase("0000", 2, ExpectedResult = 0)]
[TestCase("99099", 3, ExpectedResult = 0)]
public int Largest_product_works_if_all_spans_contain_zero(string digits, int seriesLength)
[Test]
public void Rejects_span_longer_than_string_length()
{
return new LargestSeriesProduct(digits).GetLargestProduct(seriesLength);
const string digits = "123";
const int span = 4;

Assert.Throws<ArgumentException>(() => LargestSeriesProduct.GetLargestProduct(digits, span));
}

[Ignore("Remove to run test")]
[TestCase("", ExpectedResult = 1)]
[TestCase("123", ExpectedResult = 1)]
public int Largest_product_for_empty_span_is_1(string digits)
[Test]
public void Rejects_empty_string_and_nonzero_span()
{
return new LargestSeriesProduct(digits).GetLargestProduct(0);
const string digits = "";
const int span = 1;

Assert.Throws<ArgumentException>(() => LargestSeriesProduct.GetLargestProduct(digits, span));
}

[Ignore("Remove to run test")]
[TestCase("123", 4)]
[TestCase("", 1)]
public void Cannot_take_largest_product_of_more_digits_than_input(string digits, int seriesLength)
[Test]
public void Rejects_invalid_character_in_digits()
{
Assert.Throws<ArgumentException>(() => new LargestSeriesProduct(digits).GetLargestProduct(seriesLength));
const string digits = "1234a5";
const int span = 2;

Assert.Throws<ArgumentException>(() => LargestSeriesProduct.GetLargestProduct(digits, span));
}

[Ignore("Remove to run test")]
[Test]
public void Rejects_negative_span()
{
const string digits = "12345";
const int span = -1;

Assert.Throws<ArgumentException>(() => LargestSeriesProduct.GetLargestProduct(digits, span));
}
}
}

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