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to Difference Of Squares in the C# Track

Published at Feb 08 2019 · 0 comments
Instructions
Test suite
Solution

Find the difference between the square of the sum and the sum of the squares of the first N natural numbers.

The square of the sum of the first ten natural numbers is (1 + 2 + ... + 10)² = 55² = 3025.

The sum of the squares of the first ten natural numbers is 1² + 2² + ... + 10² = 385.

Hence the difference between the square of the sum of the first ten natural numbers and the sum of the squares of the first ten natural numbers is 3025 - 385 = 2640.

Hints

This exercise requires you to process a collection of data. You can simplify your code by using LINQ (Language Integrated Query). For more information, see [this page] (https://docs.microsoft.com/en-us/dotnet/articles/standard/using-linq).

Running the tests

To run the tests, run the command dotnet test from within the exercise directory.

Initially, only the first test will be enabled. This is to encourage you to solve the exercise one step at a time. Once you get the first test passing, remove the Skip property from the next test and work on getting that test passing. Once none of the tests are skipped and they are all passing, you can submit your solution using exercism submit DifferenceOfSquares.cs

Further information

For more detailed information about the C# track, including how to get help if you're having trouble, please visit the exercism.io C# language page.

Source

Problem 6 at Project Euler http://projecteuler.net/problem=6

Submitting Incomplete Solutions

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

DifferenceOfSquaresTest.cs

// This file was auto-generated based on version 1.2.0 of the canonical data.

using Xunit;

public class DifferenceOfSquaresTest
{
    [Fact]
    public void Square_of_sum_1()
    {
        Assert.Equal(1, DifferenceOfSquares.CalculateSquareOfSum(1));
    }

    [Fact(Skip = "Remove to run test")]
    public void Square_of_sum_5()
    {
        Assert.Equal(225, DifferenceOfSquares.CalculateSquareOfSum(5));
    }

    [Fact(Skip = "Remove to run test")]
    public void Square_of_sum_100()
    {
        Assert.Equal(25502500, DifferenceOfSquares.CalculateSquareOfSum(100));
    }

    [Fact(Skip = "Remove to run test")]
    public void Sum_of_squares_1()
    {
        Assert.Equal(1, DifferenceOfSquares.CalculateSumOfSquares(1));
    }

    [Fact(Skip = "Remove to run test")]
    public void Sum_of_squares_5()
    {
        Assert.Equal(55, DifferenceOfSquares.CalculateSumOfSquares(5));
    }

    [Fact(Skip = "Remove to run test")]
    public void Sum_of_squares_100()
    {
        Assert.Equal(338350, DifferenceOfSquares.CalculateSumOfSquares(100));
    }

    [Fact(Skip = "Remove to run test")]
    public void Difference_of_squares_1()
    {
        Assert.Equal(0, DifferenceOfSquares.CalculateDifferenceOfSquares(1));
    }

    [Fact(Skip = "Remove to run test")]
    public void Difference_of_squares_5()
    {
        Assert.Equal(170, DifferenceOfSquares.CalculateDifferenceOfSquares(5));
    }

    [Fact(Skip = "Remove to run test")]
    public void Difference_of_squares_100()
    {
        Assert.Equal(25164150, DifferenceOfSquares.CalculateDifferenceOfSquares(100));
    }
}
using System;
using System.Linq;

public static class DifferenceOfSquares
{
    public static int CalculateSquareOfSum(int max)
    {
        return (int)Math.Pow(Enumerable.Range(1, max).Sum(), 2);
    }

    public static int CalculateSumOfSquares(int max)
    {
        return Enumerable.Range(1, max).Sum(i => i * i);
    }

    public static int CalculateDifferenceOfSquares(int max)
    {
        return CalculateSquareOfSum(max) - CalculateSumOfSquares(max);
    }
}

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