csharp

csharp/armstrong-numbers/ArmstrongNumbers.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Linq;
+
+public static class ArmstrongNumbers
+{
+    public static bool IsArmstrongNumber(int number)
+    {
+        var digits = number.ToString().Select(digit => int.Parse(digit.ToString())).ToList();
+        var num_digits = digits.Count;
+        var sum = 0;
+        foreach (var digit in digits)
+            sum += (int) Math.Pow(digit, num_digits);
+        return number == sum;
+    }
+}

csharp/armstrong-numbers/ArmstrongNumbers.csproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp2.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Remove="Example.cs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.5.0" />
+    <PackageReference Include="xunit" Version="2.3.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
+  </ItemGroup>
+
+</Project>

csharp/armstrong-numbers/ArmstrongNumbersTest.cs

@@ -0,0 +1,54 @@
+// This file was auto-generated based on version 1.0.0 of the canonical data.
+
+using Xunit;
+
+public class ArmstrongNumbersTest
+{
+    [Fact]
+    public void Single_digit_numbers_are_armstrong_numbers()
+    {
+        Assert.True(ArmstrongNumbers.IsArmstrongNumber(5));
+    }
+
+    [Fact]
+    public void There_are_no_2_digit_armstrong_numbers()
+    {
+        Assert.False(ArmstrongNumbers.IsArmstrongNumber(10));
+    }
+
+    [Fact]
+    public void Three_digit_number_that_is_an_armstrong_number()
+    {
+        Assert.True(ArmstrongNumbers.IsArmstrongNumber(153));
+    }
+
+    [Fact]
+    public void Three_digit_number_that_is_not_an_armstrong_number()
+    {
+        Assert.False(ArmstrongNumbers.IsArmstrongNumber(100));
+    }
+
+    [Fact]
+    public void Four_digit_number_that_is_an_armstrong_number()
+    {
+        Assert.True(ArmstrongNumbers.IsArmstrongNumber(9474));
+    }
+
+    [Fact]
+    public void Four_digit_number_that_is_not_an_armstrong_number()
+    {
+        Assert.False(ArmstrongNumbers.IsArmstrongNumber(9475));
+    }
+
+    [Fact]
+    public void Seven_digit_number_that_is_an_armstrong_number()
+    {
+        Assert.True(ArmstrongNumbers.IsArmstrongNumber(9926315));
+    }
+
+    [Fact]
+    public void Seven_digit_number_that_is_not_an_armstrong_number()
+    {
+        Assert.False(ArmstrongNumbers.IsArmstrongNumber(9926314));
+    }
+}

csharp/armstrong-numbers/README.md

@@ -0,0 +1,20 @@
+# Armstrong Numbers
+
+An [Armstrong number](https://en.wikipedia.org/wiki/Narcissistic_number) is a number that is the sum of its own digits each raised to the power of the number of digits.
+
+For example:
+
+- 9 is an Armstrong number, because `9 = 9^1 = 9`
+- 10 is *not* an Armstrong number, because `10 != 1^2 + 0^2 = 2`
+- 153 is an Armstrong number, because: `153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153`
+- 154 is *not* an Armstrong number, because: `154 != 1^3 + 5^3 + 4^3 = 1 + 125 + 64 = 190`
+
+Write some code to determine whether a number is an Armstrong number.
+
+
+## Source
+
+Wikipedia [https://en.wikipedia.org/wiki/Narcissistic_number](https://en.wikipedia.org/wiki/Narcissistic_number)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

csharp/collatz-conjecture/CollatzConjecture.cs

@@ -0,0 +1,17 @@
+using System;
+
+public static class CollatzConjecture
+{
+    // If n is even, divide n by 2 to get n / 2.
+    // If n is odd, multiply n by 3 and add 1 to get 3n + 1.
+    public static int Steps(int number)
+    {
+        if (number < 1) throw new ArgumentException();
+        int cnt = 0;
+        while (number != 1) {
+            number = number % 2 == 0 ? number / 2 : 3 * number + 1;
+            cnt ++;
+        }
+        return cnt;
+    }
+}

csharp/collatz-conjecture/CollatzConjecture.csproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>    
+    <TargetFramework>netcoreapp2.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Remove="Example.cs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.5.0" />
+    <PackageReference Include="xunit" Version="2.3.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
+  </ItemGroup>
+
+</Project>

csharp/collatz-conjecture/CollatzConjectureTest.cs

@@ -0,0 +1,43 @@
+// This file was auto-generated based on version 1.1.1 of the canonical data.
+
+using Xunit;
+using System;
+
+public class CollatzConjectureTest
+{
+    [Fact]
+    public void Zero_steps_for_one()
+    {
+        Assert.Equal(0, CollatzConjecture.Steps(1));
+    }
+
+    [Fact]
+    public void Divide_if_even()
+    {
+        Assert.Equal(4, CollatzConjecture.Steps(16));
+    }
+
+    [Fact]
+    public void Even_and_odd_steps()
+    {
+        Assert.Equal(9, CollatzConjecture.Steps(12));
+    }
+
+    [Fact]
+    public void Large_number_of_even_and_odd_steps()
+    {
+        Assert.Equal(152, CollatzConjecture.Steps(1000000));
+    }
+
+    [Fact]
+    public void Zero_is_an_error()
+    {
+        Assert.Throws<ArgumentException>(() => CollatzConjecture.Steps(0));
+    }
+
+    [Fact]
+    public void Negative_value_is_an_error()
+    {
+        Assert.Throws<ArgumentException>(() => CollatzConjecture.Steps(-15));
+    }
+}

csharp/collatz-conjecture/README.md

@@ -0,0 +1,35 @@
+# Collatz Conjecture
+
+The Collatz Conjecture or 3x+1 problem can be summarized as follows:
+
+Take any positive integer n. If n is even, divide n by 2 to get n / 2. If n is
+odd, multiply n by 3 and add 1 to get 3n + 1. Repeat the process indefinitely.
+The conjecture states that no matter which number you start with, you will
+always reach 1 eventually.
+
+Given a number n, return the number of steps required to reach 1.
+
+## Examples
+
+Starting with n = 12, the steps would be as follows:
+
+0. 12
+1. 6
+2. 3
+3. 10
+4. 5
+5. 16
+6. 8
+7. 4
+8. 2
+9. 1
+
+Resulting in 9 steps. So for input n = 12, the return value would be 9.
+
+
+## Source
+
+An unsolved problem in mathematics named after mathematician Lothar Collatz [https://en.wikipedia.org/wiki/3x_%2B_1_problem](https://en.wikipedia.org/wiki/3x_%2B_1_problem)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

csharp/grade-school/GradeSchool.cs

@@ -1,20 +1,26 @@
-using System;
 using System.Collections.Generic;
+using System.Linq;
 
 public class School
 {
+    private Dictionary<int, List<string>> roster = new Dictionary<int, List<string>>();
+
     public void Add(string student, int grade)
     {
-        throw new NotImplementedException("You need to implement this function.");
+        if (roster.ContainsKey(grade))
+            roster[grade].Add(student);
+        else
+            roster.Add(grade, new List<string> {student});
     }
 
     public IEnumerable<string> Roster()
-    {
-        throw new NotImplementedException("You need to implement this function.");
-    }
+        => roster.Keys
+            .OrderBy(g => g)
+            .SelectMany(g => Grade(g))
+            .ToList();
 
     public IEnumerable<string> Grade(int grade)
-    {
-        throw new NotImplementedException("You need to implement this function.");
-    }
-}
+        => roster.ContainsKey(grade)
+            ? roster[grade].OrderBy(g => g).ToList()
+            : new List<string>();
+}

csharp/grade-school/GradeSchoolTest.cs

@@ -14,21 +14,21 @@ public class GradeSchoolTest
         Assert.Equal(expected, actual);
     }
 
-    [Fact(Skip = "Remove to run test")]
+    [Fact]
     public void Adding_more_students_adds_them_to_the_sorted_roster()
     {
         var school = new School();
         school.Add("Blair", 2);
         school.Add("James", 2);
         school.Add("Paul", 2);
-       
+
         var actual = school.Roster();
 
         var expected = new[] { "Blair", "James", "Paul" };
-        Assert.Equal(expected, actual );
+        Assert.Equal(expected, actual);
     }
 
-    [Fact(Skip = "Remove to run test")]
+    [Fact]
     public void Adding_students_to_different_grades_adds_them_to_the_same_sorted_roster()
     {
         var school = new School();
@@ -41,31 +41,31 @@ public class GradeSchoolTest
         Assert.Equal(expected, actual);
     }
 
-    [Fact(Skip = "Remove to run test")]
+    [Fact]
     public void Grade_returns_the_students_in_that_grade_in_alphabetical_order()
     {
         var school = new School();
         school.Add("Franklin", 5);
         school.Add("Bradley", 5);
         school.Add("Jeff", 1);
-        
+
         var actual = school.Grade(5);
 
         var expected = new[] { "Bradley", "Franklin" };
         Assert.Equal(expected, actual);
     }
 
-    [Fact(Skip = "Remove to run test")]
+    [Fact]
     public void Grade_returns_an_empty_list_if_there_are_no_students_in_that_grade()
     {
         var school = new School();
 
-        var actual = school.Grade(1); 
+        var actual = school.Grade(1);
 
         Assert.Empty(actual);
     }
 
-    [Fact(Skip = "Remove to run test")]
+    [Fact]
     public void Student_names_with_grades_are_displayed_in_the_same_sorted_roster()
     {
         var school = new School();
@@ -76,10 +76,10 @@ public class GradeSchoolTest
         school.Add("Alex", 2);
         school.Add("Jim", 3);
         school.Add("Charlie", 1);
-              
+
         var actual = school.Roster();
-        
+
         var expected = new[] { "Anna", "Barb", "Charlie", "Alex", "Peter", "Zoe", "Jim" };
         Assert.Equal(expected, actual);
     }
-}
+}

csharp/kindergarten-garden/KindergartenGarden.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+
+public enum Plant
+{
+    Violets,
+    Radishes,
+    Clover,
+    Grass
+}
+
+public class KindergartenGarden
+{    
+    public KindergartenGarden(string diagram)
+    {
+    }
+
+    public KindergartenGarden(string diagram, IEnumerable<string> students)
+    {
+    }
+
+    public IEnumerable<Plant> Plants(string student)
+    {
+        throw new NotImplementedException("You need to implement this function.");
+    }
+}

csharp/kindergarten-garden/KindergartenGarden.csproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>    
+    <TargetFramework>netcoreapp2.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Remove="Example.cs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.5.0" />
+    <PackageReference Include="xunit" Version="2.3.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
+  </ItemGroup>
+
+</Project>

csharp/kindergarten-garden/KindergartenGardenTest.cs

@@ -0,0 +1,69 @@
+// This file was auto-generated based on version 1.0.0 of the canonical data.
+
+using Xunit;
+
+public class KindergartenGardenTest
+{
+    [Fact]
+    public void Partial_garden_garden_with_single_student()
+    {
+        var sut = new KindergartenGarden("RC\nGG");
+        Assert.Equal(new[] { Plant.Radishes, Plant.Clover, Plant.Grass, Plant.Grass }, sut.Plants("Alice"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Partial_garden_different_garden_with_single_student()
+    {
+        var sut = new KindergartenGarden("VC\nRC");
+        Assert.Equal(new[] { Plant.Violets, Plant.Clover, Plant.Radishes, Plant.Clover }, sut.Plants("Alice"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Partial_garden_garden_with_two_students()
+    {
+        var sut = new KindergartenGarden("VVCG\nVVRC");
+        Assert.Equal(new[] { Plant.Clover, Plant.Grass, Plant.Radishes, Plant.Clover }, sut.Plants("Bob"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Partial_garden_multiple_students_for_the_same_garden_with_three_students_second_students_garden()
+    {
+        var sut = new KindergartenGarden("VVCCGG\nVVCCGG");
+        Assert.Equal(new[] { Plant.Clover, Plant.Clover, Plant.Clover, Plant.Clover }, sut.Plants("Bob"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Partial_garden_multiple_students_for_the_same_garden_with_three_students_third_students_garden()
+    {
+        var sut = new KindergartenGarden("VVCCGG\nVVCCGG");
+        Assert.Equal(new[] { Plant.Grass, Plant.Grass, Plant.Grass, Plant.Grass }, sut.Plants("Charlie"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Full_garden_first_students_garden()
+    {
+        var sut = new KindergartenGarden("VRCGVVRVCGGCCGVRGCVCGCGV\nVRCCCGCRRGVCGCRVVCVGCGCV");
+        Assert.Equal(new[] { Plant.Violets, Plant.Radishes, Plant.Violets, Plant.Radishes }, sut.Plants("Alice"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Full_garden_second_students_garden()
+    {
+        var sut = new KindergartenGarden("VRCGVVRVCGGCCGVRGCVCGCGV\nVRCCCGCRRGVCGCRVVCVGCGCV");
+        Assert.Equal(new[] { Plant.Clover, Plant.Grass, Plant.Clover, Plant.Clover }, sut.Plants("Bob"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Full_garden_second_to_last_students_garden()
+    {
+        var sut = new KindergartenGarden("VRCGVVRVCGGCCGVRGCVCGCGV\nVRCCCGCRRGVCGCRVVCVGCGCV");
+        Assert.Equal(new[] { Plant.Grass, Plant.Clover, Plant.Clover, Plant.Grass }, sut.Plants("Kincaid"));
+    }
+
+    [Fact(Skip = "Remove to run test")]
+    public void Full_garden_last_students_garden()
+    {
+        var sut = new KindergartenGarden("VRCGVVRVCGGCCGVRGCVCGCGV\nVRCCCGCRRGVCGCRVVCVGCGCV");
+        Assert.Equal(new[] { Plant.Grass, Plant.Violets, Plant.Clover, Plant.Violets }, sut.Plants("Larry"));
+    }
+}

csharp/kindergarten-garden/README.md

@@ -0,0 +1,68 @@
+# Kindergarten Garden
+
+Given a diagram, determine which plants each child in the kindergarten class is
+responsible for.
+
+The kindergarten class is learning about growing plants. The teacher
+thought it would be a good idea to give them actual seeds, plant them in
+actual dirt, and grow actual plants.
+
+They've chosen to grow grass, clover, radishes, and violets.
+
+To this end, the children have put little cups along the window sills, and
+planted one type of plant in each cup, choosing randomly from the available
+types of seeds.
+
+```text
+[window][window][window]
+........................ # each dot represents a cup
+........................
+```
+
+There are 12 children in the class:
+
+- Alice, Bob, Charlie, David,
+- Eve, Fred, Ginny, Harriet,
+- Ileana, Joseph, Kincaid, and Larry.
+
+Each child gets 4 cups, two on each row. Their teacher assigns cups to
+the children alphabetically by their names.
+
+The following diagram represents Alice's plants:
+
+```text
+[window][window][window]
+VR......................
+RG......................
+```
+
+In the first row, nearest the windows, she has a violet and a radish.  In the
+second row she has a radish and some grass.
+
+Your program will be given the plants from left-to-right starting with
+the row nearest the windows. From this, it should be able to determine
+which plants belong to each student.
+
+For example, if it's told that the garden looks like so:
+
+```text
+[window][window][window]
+VRCGVVRVCGGCCGVRGCVCGCGV
+VRCCCGCRRGVCGCRVVCVGCGCV
+```
+
+Then if asked for Alice's plants, it should provide:
+
+- Violets, radishes, violets, radishes
+
+While asking for Bob's plants would yield:
+
+- Clover, grass, clover, clover
+
+
+## Source
+
+Random musings during airplane trip. [http://jumpstartlab.com](http://jumpstartlab.com)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.