Puzzle: Singer Name to Group Type

Posted on December 31, 2017

The Challenge

This challenge comes from listener Patrick Berry of Jasper, Ala. Name a famous singer — 3 letters in the first name, 5 letters in the last. Drop the middle letter of the last name and rearrange the result to name a variety of singing group. What is it?

The Solution

Synopsis

Fun, easy! I was fortunate to have a file lying around with singer names, and it was easy enough to go to Wikipedia to grab a list of musical group types.

Also: woo-woo! I Almost solved it without a single bug! I was able to fix my solitary bug during a debug session, so I can honestly say it ran the first time.

Techniques Used

• Linq
• File-IO
• String-manipuation
• Just for a fun, anonymous functions (delegates)

The Code

string singerFile = @"Singers.txt";
string groupTypeFile = "MusicalGroupTypeList.txt";

//Make a function to sort the letters in a string, converting 
//to lower case, and removing all but letters
Func<string, string> sortLetters = (g) => g
                            .Where(c => char.IsLetter(c))
                            .Select(c => char.ToLower(c))
                            .OrderBy(c => c)
                            .Aggregate("", (p, c) => p + c);

//The dictionary key is the sorted letters; the 
//value is the original string
var groupTypeDic = new Dictionary<string, string>();

//Open the file of group types; use it to build the dictionary
using (StreamReader sr = File.OpenText(groupTypeFile)) {
    while (sr.Peek() != -1) {
        string grpType = sr.ReadLine();

        string key = sortLetters(grpType);
        if (!groupTypeDic.ContainsKey(key)) {
            groupTypeDic.Add(key, grpType);
        }
    }
}

//Now read all the singers from the file
using (StreamReader sr = File.OpenText(singerFile)) {
    while (sr.Peek() != -1) {
        string singerName = sr.ReadLine();
        string[] tokens = singerName.Split(' ');
        int lastIndex = tokens.Length - 1;
        if (tokens.Length > 1 
            && tokens[0].Length == 3 
            && tokens[lastIndex].Length == 5) {
            //Combine the first name and /1st 2 letters of last name, 
            //plus the last 2 letters of last name
            string remove3rdLetterLastName = tokens[0]
                                       + tokens[lastIndex].Substring(0, 2)
                                       + tokens[lastIndex].Substring(3);
            string sorted = sortLetters(remove3rdLetterLastName);
            //Does the dictionary contain the sorted letters?
            if (groupTypeDic.ContainsKey(sorted)) {
               //Yipee! Found a solution
               txtSolution.Text = $"{singerName} → {groupTypeDic[sorted]}";
            }
        }
    }
}

 

Explanation

Remember, if two words are anagrams, then their sorted letters are the same.

• “Bob Dylan” → “bobdyan” →”abbdnoy”
• “Boy Band” → “boyband” → “abbdnoy”

Encapsulate that Functionality in an Anonymous Function named ‘sortLetters’

Func<string, string> sortLetters = (g) => g
      .Where(c => char.IsLetter(c))
      .Select(c => char.ToLower(c))
      .OrderBy(c => c)
      .Aggregate("", (p, c) => p + c);

Here I create a function variable named ‘sortLetters’ that has one input parameter (string) and returns another string.

Inside the function, the input parameter (‘g’) is treated like a list of char, because I invoke Linq methods on it.

• The ‘where-clause’ removes any spaces or other funky chars
• The ‘select-clause’ converts ‘BobDylan’ → ‘bobdylan’
• The ‘OrderBy’ clause converts ‘bobdylan’ to ‘abbdnoy’
• The ‘Aggregate’ clause converts the result back to a string

Read all the Group Types, Hold Each in Variable ‘grpType’

using (StreamReader sr = File.OpenText(groupTypeFile)) {
 while (sr.Peek() != -1) {
 string grpType = sr.ReadLine();

Store the Group Type in a Dictionary

string key = sortLetters(grpType); 
if (!groupTypeDic.ContainsKey(key)) { 
    groupTypeDic.Add(key, grpType); 
}

Read the Singers File, Store Each in Variable ‘singerName’

using (StreamReader sr = File.OpenText(singerFile)) { 
    while (sr.Peek() != -1) { 
        string singerName = sr.ReadLine();

Split the Singer Name into Parts, Proceed if Lengths are 3/5

string[] tokens = singerName.Split(' '); 
int lastIndex = tokens.Length - 1; 
if (tokens.Length > 1 
    && tokens[0].Length == 3 
    && tokens[lastIndex].Length == 5) {

• The ‘split’ function returns an array of string

Remove 3rd Letter From Singer’s Name, Sort the Letters

 string remove3rdLetterLastName = tokens[0] 
                                  + tokens[lastIndex].Substring(0, 2) 
                                  + tokens[lastIndex].Substring(3); 
string sorted = sortLetters(remove3rdLetterLastName);

Here we concatenate the first name with the first 2 letters of last name and then the last 2 letters of the last name. Re-use the anonymous function to sort the letters.

If the Sorted Letters Match a Dictionary Entry, Add the Result to the TextBox

if (groupTypeDic.ContainsKey(sorted)) { 
    //Yipee! Found a solution 
    txtSolution.Text = $"{singerName} → {groupTypeDic[sorted]}"; 
}

Get the Code

You can download my code here. Note that you will need to create a (free) dropbox account to access the link.