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justin-vanwinkle/PowerDMS_Interview.cs

Created July 12, 2018 01:11
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  1. justin-vanwinkle created this gist Jul 12, 2018.
    77 changes: 77 additions & 0 deletions PowerDMS_Interview.cs
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    Original file line number Diff line number Diff line change
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    using System.Collections.Generic;
    using System.Linq;

    namespace PowerDMS.Main
    {
    public class Interview
    {
    /// <summary>
    /// Compares two strings for an anagram
    /// </summary>
    /// <param name="str1">First string for comparison</param>
    /// <param name="str2">Second string for comparison</param>
    /// <returns>True if the two strings form an anagram, otherwise false</returns>
    public bool IsAnagram(string str1, string str2)
    {
    // **Assumption** Leading/trailing whitespace is acceptable input, but not considered for comparison.
    str1 = str1.Trim();
    str2 = str2.Trim();

    // internal whitespace breaks the definition of an anagram
    if (str1.Any(char.IsWhiteSpace) || str2.Any(char.IsWhiteSpace))
    {
    return false;
    }

    // null strings break the definition of an anagram
    if (string.IsNullOrWhiteSpace(str1) || string.IsNullOrWhiteSpace(str2))
    {
    return false;
    }

    var str1CharCounts = TallyChars(str1);
    var str2CharCounts = TallyChars(str2);

    // check for differring keys and key counts
    if (str1CharCounts.Count != str2CharCounts.Count ||
    !str1CharCounts.Keys.All(x => str2CharCounts.ContainsKey(x)))
    {
    return false;
    }

    foreach (var (key, value) in str1CharCounts)
    {
    if (str2CharCounts[key] != value)
    {
    return false;
    }
    }

    return true;
    }

    /// <summary>
    /// Counts the occurrence of each letter in a given string
    /// </summary>
    /// <param name="str">The string containing characters to tally</param>
    /// <returns>A Dictionary mapping the letters that occurred in the string to the total number of times that they occurred in the string</returns>
    public Dictionary<char, int> TallyChars(string str)
    {
    var chars = str.ToCharArray(0, str.Length);
    var map = new Dictionary<char, int>();
    foreach (var c in chars)
    {
    if (map.TryGetValue(c, out var currentCount))
    {
    map[c] = currentCount + 1;
    }
    else
    {
    map.Add(c, 1);
    }
    }

    return map;
    }
    }
    }
    78 changes: 78 additions & 0 deletions PowerDMS_Interview_Tests.cs
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    Original file line number Diff line number Diff line change
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    using FluentAssertions;
    using PowerDMS.Main;
    using Xunit;

    namespace PowerDMS.Tests
    {
    public class InterviewTests
    {
    private Interview Interview { get; }

    public InterviewTests()
    {
    Interview = new Interview();
    }

    [Fact]
    public void Returns_True_If_Anagram()
    {
    var str1 = "cinema";
    var str2 = "iceman";
    Interview.IsAnagram(str1, str2).Should().BeTrue();
    }

    [Fact]
    public void Returns_False_If_Two_Strings_Have_Same_Length_Different_Letters()
    {
    var str1 = "ars";
    var str2 = "set";

    Interview.IsAnagram(str1, str2).Should().BeFalse();
    }

    [Fact]
    public void Returns_False_If_Two_Strings_Have_Differring_Lengths()
    {
    var str1 = "arst";
    var str2 = "qw";

    Interview.IsAnagram(str1, str2).Should().BeFalse();
    }

    [Fact]
    public void Returns_False_If_Strings_Have_Same_Letters_Different_Count()
    {
    var str1 = "aarr";
    var str2 = "arrr";

    Interview.IsAnagram(str1, str2).Should().BeFalse();
    }

    [Fact]
    public void Returns_False_If_Strings_Contain_Whitespace()
    {
    var str1 = "aa rr";
    var str2 = "aa rr";

    Interview.IsAnagram(str1, str2).Should().BeFalse();
    }

    [Fact]
    public void Returns_False_If_String_Is_Whitespace()
    {
    var str1 = "";
    var str2 = "aarr";

    Interview.IsAnagram(str1, str2).Should().BeFalse();
    }

    [Fact]
    public void Leading_And_Trailing_Whitespace_Are_Acceptable()
    {
    var str1 = " arst";
    var str2 = "sart ";

    Interview.IsAnagram(str1, str2).Should().BeTrue();
    }
    }
    }