Anagram

Anagram

Medium

Introduction

At a garage sale, you find a lovely vintage typewriter at a bargain price! Excitedly, you rush home, insert a sheet of paper, and start typing away. However, your excitement wanes when you examine the output: all words are garbled! For example, it prints "stop" instead of "post" and "least" instead of "stale." Carefully, you try again, but now it prints "spot" and "slate." After some experimentation, you find there is a random delay before each letter is printed, which messes up the order. You now understand why they sold it for so little money!

You realize this quirk allows you to generate anagrams, which are words formed by rearranging the letters of another word. Pleased with your finding, you spend the rest of the day generating hundreds of anagrams.

Instructions

Your task is to, given a target word and a set of candidate words, to find the subset of the candidates that are anagrams of the target.

An anagram is a rearrangement of letters to form a new word: for example "owns" is an anagram of "snow". A word is not its own anagram: for example, "stop" is not an anagram of "stop".

The target and candidates are words of one or more ASCII alphabetic characters (A-Z and a-z). Lowercase and uppercase characters are equivalent: for example, "PoTS" is an anagram of "sTOp", but StoP is not an anagram of sTOp. The anagram set is the subset of the candidate set that are anagrams of the target (in any order). Words in the anagram set should have the same letter case as in the candidate set.

Given the target "stone" and candidates "stone", "tones", "banana", "tons", "notes", "Seton", the anagram set is "tones", "notes", "Seton".

Track Specific Notes

For purposes of this exercise, a word is not considered to be an anagram of itself.

Running and testing your solutions

From the command line

Simply type make chez if you're using ChezScheme or make guile if you're using GNU Guile. Sometimes the name for the scheme binary on your system will differ from the defaults. When this is the case, you'll need to tell make by running make chez chez=your-chez-binary or make guile guile=your-guile-binary.

From a REPL

  • Enter (load "test.scm") at the repl prompt.
  • Develop your solution in anagram.scm reloading as you go.
  • Run (test) to check your solution.

Failed Test Cases

If some of the test cases fail, you should see the failing input and the expected output. The failing input is presented as a list because the tests call your solution by (apply anagram input-list). To learn more about apply see The Scheme Programming Language -- Chapter 5

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