Add Anagram solution

Author: blogscot

anagram/Cargo.toml

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+[package]
+name = "anagram"
+version = "0.0.0"

anagram/README.md

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+# Anagram
+
+Given a word and a list of possible anagrams, select the correct sublist.
+
+Given `"listen"` and a list of candidates like `"enlists" "google"
+"inlets" "banana"` the program should return a list containing
+`"inlets"`.
+
+## Rust Installation
+
+Refer to the [exercism help page][help-page] for Rust installation and learning
+resources.
+
+## Writing the Code
+
+Execute the tests with:
+
+```bash
+$ cargo test
+```
+
+All but the first test have been ignored. After you get the first test to
+pass, open the tests source file which is located in the `tests` directory
+and remove the `#[ignore]` flag from the next test and get the tests to pass
+again. Each separate test is a function with `#[test]` flag above it.
+Continue, until you pass every test. 
+
+If you wish to run all tests without editing the tests source file, use:
+
+```bash
+$ cargo test -- --ignored
+```
+
+To run a specific test, for example `some_test`, you can use:
+
+```bash
+$ cargo test some_test
+```
+
+If the specific test is ignored use:
+
+```bash
+$ cargo test some_test -- --ignored
+```
+
+To learn more about Rust tests refer to the [online test documentation][rust-tests]
+
+Make sure to read the [Modules](https://doc.rust-lang.org/book/second-edition/ch07-00-modules.html) chapter if you
+haven't already, it will help you with organizing your files.
+
+## Feedback, Issues, Pull Requests
+
+The [exercism/rust](https://github.com/exercism/rust) repository on GitHub is the home for all of the Rust exercises. If you have feedback about an exercise, or want to help implement new exercises, head over there and create an issue. Members of the rust track team are happy to help!
+
+If you want to know more about Exercism, take a look at the [contribution guide](https://github.com/exercism/docs/blob/master/contributing-to-language-tracks/README.md).
+
+[help-page]: http://exercism.io/languages/rust
+[modules]: https://doc.rust-lang.org/book/second-edition/ch07-00-modules.html
+[cargo]: https://doc.rust-lang.org/book/second-edition/ch14-00-more-about-cargo.html
+[rust-tests]: https://doc.rust-lang.org/book/second-edition/ch11-02-running-tests.html
+
+## Source
+
+Inspired by the Extreme Startup game [https://github.com/rchatley/extreme_startup](https://github.com/rchatley/extreme_startup)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

anagram/src/lib.rs

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+use std::collections::HashSet;
+
+pub fn anagrams_for<'a>(word: &str, possible_anagrams: &'a [&str]) -> HashSet<&'a str> {
+  let anagrams = possible_anagrams.to_vec();
+  anagrams
+    .iter()
+    .cloned()
+    .filter(|&anagram| anagram.to_lowercase() != word.to_lowercase() && compare(anagram, word))
+    .collect()
+}
+
+fn compare(left: &str, right: &str) -> bool {
+  let mut right = right
+    .chars()
+    .map(|chr| chr.to_lowercase().to_string())
+    .collect::<Vec<_>>();
+  let mut left = left
+    .chars()
+    .map(|chr| chr.to_lowercase().to_string())
+    .collect::<Vec<_>>();
+  left.sort();
+  right.sort();
+  left == right
+}

anagram/tests/anagrams.rs

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+extern crate anagram;
+
+use std::collections::HashSet;
+use std::iter::FromIterator;
+
+fn process_anagram_case(word: &str, inputs: &[&str], expected: &[&str]) {
+  let result = anagram::anagrams_for(word, inputs);
+
+  let expected: HashSet<&str> = HashSet::from_iter(expected.iter().cloned());
+
+  assert_eq!(result, expected);
+}
+
+#[test]
+fn test_no_matches() {
+  let word = "diaper";
+
+  let inputs = ["hello", "world", "zombies", "pants"];
+
+  let outputs = vec![];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_detect_simple_anagram() {
+  let word = "ant";
+
+  let inputs = ["tan", "stand", "at"];
+
+  let outputs = vec!["tan"];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_does_not_confuse_different_duplicates() {
+  let word = "galea";
+
+  let inputs = ["eagle"];
+
+  let outputs = vec![];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_eliminate_anagram_subsets() {
+  let word = "good";
+
+  let inputs = ["dog", "goody"];
+
+  let outputs = vec![];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_detect_anagram() {
+  let word = "listen";
+
+  let inputs = ["enlists", "google", "inlets", "banana"];
+
+  let outputs = vec!["inlets"];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_multiple_anagrams() {
+  let word = "allergy";
+
+  let inputs = [
+    "gallery",
+    "ballerina",
+    "regally",
+    "clergy",
+    "largely",
+    "leading",
+  ];
+
+  let outputs = vec!["gallery", "regally", "largely"];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_case_insensitive_anagrams() {
+  let word = "Orchestra";
+
+  let inputs = ["cashregister", "Carthorse", "radishes"];
+
+  let outputs = vec!["Carthorse"];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_unicode_anagrams() {
+  let word = "ΑΒΓ";
+
+  // These words don't make sense, they're just greek letters cobbled together.
+  let inputs = ["ΒΓΑ", "ΒΓΔ", "γβα"];
+
+  let outputs = vec!["ΒΓΑ", "γβα"];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_misleading_unicode_anagrams() {
+  // Despite what a human might think these words different letters, the input uses Greek A and B
+  // while the list of potential anagrams uses Latin A and B.
+  let word = "ΑΒΓ";
+
+  let inputs = ["ABΓ"];
+
+  let outputs = vec![];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_does_not_detect_a_word_as_its_own_anagram() {
+  let word = "banana";
+
+  let inputs = ["banana"];
+
+  let outputs = vec![];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_does_not_detect_a_differently_cased_word_as_its_own_anagram() {
+  let word = "banana";
+
+  let inputs = ["bAnana"];
+
+  let outputs = vec![];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_does_not_detect_a_differently_cased_unicode_word_as_its_own_anagram() {
+  let word = "ΑΒΓ";
+
+  let inputs = ["ΑΒγ"];
+
+  let outputs = vec![];
+
+  process_anagram_case(word, &inputs, &outputs);
+}
+
+#[test]
+fn test_same_bytes_different_chars() {
+  let word = "a⬂"; // 61 E2 AC 82
+
+  let inputs = ["€a"]; // E2 82 AC 61
+
+  let outputs = vec![];
+
+  process_anagram_case(word, &inputs, &outputs);
+}