Add "Anagram" exercise (#52)

* add anagram exercise

* add rational-numbers & complex-numbers to foregone

* add missing author

* Unimplement SetEq::ne

* include=false for last 2 tests in tests.toml

* remove rational-numbers from foregone

* add comments to excluded test cases

config.json

@@ -182,10 +182,23 @@
         ],
         "prerequisites": [],
         "difficulty": 3
+      },
+      {
+        "slug": "anagram",
+        "name": "Anagram",
+        "uuid": "ffce515d-69e9-48a6-91ec-8593606b15f9",
+        "practices": [
+          "traits",
+          "strings",
+          "arrays"
+        ],
+        "prerequisites": [],
+        "difficulty": 5
       }
     ],
     "foregone": [
-      "hangman"
+      "hangman",
+      "complex-numbers"
     ]
   },
   "concepts": [

exercises/practice/anagram/.docs/instructions.md

@@ -0,0 +1,13 @@
+# 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"`.

exercises/practice/anagram/.docs/introduction.md

@@ -0,0 +1,12 @@
+# 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.

exercises/practice/anagram/.meta/config.json

@@ -0,0 +1,20 @@
+{
+  "authors": [
+    "misicnenad"
+  ],
+  "files": {
+    "solution": [
+      "src/lib.cairo",
+      "Scarb.toml"
+    ],
+    "test": [
+      "src/tests.cairo"
+    ],
+    "example": [
+      ".meta/example.cairo"
+    ]
+  },
+  "blurb": "Given a word and a list of possible anagrams, select the correct sublist.",
+  "source": "Inspired by the Extreme Startup game",
+  "source_url": "https://github.com/rchatley/extreme_startup"
+}

exercises/practice/anagram/.meta/example.cairo

@@ -0,0 +1,138 @@
+use alexandria_sorting::MergeSort;
+
+#[derive(Drop, Debug)]
+struct Set {
+    values: Array<ByteArray>
+}
+
+#[generate_trait]
+impl SetImpl of SetTrait {
+    fn new(values: Array<ByteArray>) -> Set {
+        Set { values }
+    }
+}
+
+impl SetEq of PartialEq<Set> {
+    fn eq(lhs: @Set, rhs: @Set) -> bool {
+        let len = lhs.values.len();
+        if len != rhs.values.len() {
+            return false;
+        }
+        let mut i = 0;
+        loop {
+            if i == len {
+                break true;
+            }
+            let l_item = lhs.values.at(i);
+            let mut contained = false;
+            let mut j = 0;
+            while j != len {
+                if IgnoreCase::eq(l_item, rhs.values.at(j)) {
+                    contained = true;
+                    break;
+                }
+                j += 1;
+            };
+            if !contained {
+                break false;
+            }
+            i += 1;
+        }
+    }
+
+    fn ne(lhs: @Set, rhs: @Set) -> bool {
+        !(lhs == rhs)
+    }
+}
+
+pub fn anagrams_for(word: @ByteArray, inputs: @Set) -> Set {
+    let mut word_sorted = @sort(word);
+    let mut anagrams = Set { values: array![] };
+    let mut i = inputs.values.len();
+
+    while i != 0 {
+        i -= 1;
+        let candidate = inputs.values[i];
+        let mut candidate_sorted = @sort(candidate);
+
+        let is_anagram = word.len() == candidate.len()
+            && IgnoreCase::ne(word, candidate)
+            && IgnoreCaseArray::eq(word_sorted, candidate_sorted);
+
+        if is_anagram {
+            anagrams.values.append(format!("{candidate}"));
+        }
+    };
+
+    anagrams
+}
+
+impl IgnoreCase of PartialEq<ByteArray> {
+    fn eq(lhs: @ByteArray, rhs: @ByteArray) -> bool {
+        let len = lhs.len();
+        if len != rhs.len() {
+            return false;
+        }
+        let mut i = 0;
+        loop {
+            if i == len {
+                break true;
+            }
+            if lowercase(@lhs[i]) != lowercase(@rhs[i]) {
+                break false;
+            }
+            i += 1;
+        }
+    }
+
+    fn ne(lhs: @ByteArray, rhs: @ByteArray) -> bool {
+        !IgnoreCase::eq(lhs, rhs)
+    }
+}
+
+fn sort(word: @ByteArray) -> Array<u8> {
+    MergeSort::sort(to_char_array(word).span())
+}
+
+fn to_char_array(word: @ByteArray) -> Array<u8> {
+    let mut chars: Array<u8> = array![];
+    let mut i = word.len();
+    while i != 0 {
+        i -= 1;
+        chars.append(lowercase(@word[i]));
+    };
+    chars
+}
+
+impl IgnoreCaseArray of PartialEq<Array<u8>> {
+    fn eq(lhs: @Array<u8>, rhs: @Array<u8>) -> bool {
+        if lhs.len() != rhs.len() {
+            return false;
+        }
+        let mut i = lhs.len();
+        loop {
+            if i == 0 {
+                break true;
+            }
+            i -= 1;
+            if lowercase(lhs.at(i)) != lowercase(rhs.at(i)) {
+                break false;
+            }
+        }
+    }
+
+    fn ne(lhs: @Array<u8>, rhs: @Array<u8>) -> bool {
+        !IgnoreCaseArray::eq(lhs, rhs)
+    }
+}
+
+fn lowercase(char: @u8) -> u8 {
+    if *char < 97 {
+        *char + 32
+    } else {
+        *char
+    }
+}
+
+#[cfg(test)]
+mod tests;

exercises/practice/anagram/.meta/tests.toml

@@ -0,0 +1,90 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[dd40c4d2-3c8b-44e5-992a-f42b393ec373]
+description = "no matches"
+
+[b3cca662-f50a-489e-ae10-ab8290a09bdc]
+description = "detects two anagrams"
+include = false
+
+[03eb9bbe-8906-4ea0-84fa-ffe711b52c8b]
+description = "detects two anagrams"
+reimplements = "b3cca662-f50a-489e-ae10-ab8290a09bdc"
+
+[a27558ee-9ba0-4552-96b1-ecf665b06556]
+description = "does not detect anagram subsets"
+
+[64cd4584-fc15-4781-b633-3d814c4941a4]
+description = "detects anagram"
+
+[99c91beb-838f-4ccd-b123-935139917283]
+description = "detects three anagrams"
+
+[78487770-e258-4e1f-a646-8ece10950d90]
+description = "detects multiple anagrams with different case"
+
+[1d0ab8aa-362f-49b7-9902-3d0c668d557b]
+description = "does not detect non-anagrams with identical checksum"
+
+[9e632c0b-c0b1-4804-8cc1-e295dea6d8a8]
+description = "detects anagrams case-insensitively"
+
+[b248e49f-0905-48d2-9c8d-bd02d8c3e392]
+description = "detects anagrams using case-insensitive subject"
+
+[f367325c-78ec-411c-be76-e79047f4bd54]
+description = "detects anagrams using case-insensitive possible matches"
+
+[7cc195ad-e3c7-44ee-9fd2-d3c344806a2c]
+description = "does not detect an anagram if the original word is repeated"
+include = false
+
+[630abb71-a94e-4715-8395-179ec1df9f91]
+description = "does not detect an anagram if the original word is repeated"
+reimplements = "7cc195ad-e3c7-44ee-9fd2-d3c344806a2c"
+
+[9878a1c9-d6ea-4235-ae51-3ea2befd6842]
+description = "anagrams must use all letters exactly once"
+
+[85757361-4535-45fd-ac0e-3810d40debc1]
+description = "words are not anagrams of themselves (case-insensitive)"
+include = false
+
+[68934ed0-010b-4ef9-857a-20c9012d1ebf]
+description = "words are not anagrams of themselves"
+reimplements = "85757361-4535-45fd-ac0e-3810d40debc1"
+
+[589384f3-4c8a-4e7d-9edc-51c3e5f0c90e]
+description = "words are not anagrams of themselves even if letter case is partially different"
+reimplements = "85757361-4535-45fd-ac0e-3810d40debc1"
+
+[ba53e423-7e02-41ee-9ae2-71f91e6d18e6]
+description = "words are not anagrams of themselves even if letter case is completely different"
+reimplements = "85757361-4535-45fd-ac0e-3810d40debc1"
+
+[a0705568-628c-4b55-9798-82e4acde51ca]
+description = "words other than themselves can be anagrams"
+include = false
+
+[33d3f67e-fbb9-49d3-a90e-0beb00861da7]
+description = "words other than themselves can be anagrams"
+reimplements = "a0705568-628c-4b55-9798-82e4acde51ca"
+
+[a6854f66-eec1-4afd-a137-62ef2870c051]
+description = "handles case of greek letters"
+# Cairo supports only ASCII
+include = false
+
+[fd3509e5-e3ba-409d-ac3d-a9ac84d13296]
+description = "different characters may have the same bytes"
+# Cairo supports only ASCII
+include = false

exercises/practice/anagram/Scarb.toml

@@ -0,0 +1,7 @@
+[package]
+name = "anagram"
+version = "0.1.0"
+edition = "2023_11"
+
+[dependencies]
+alexandria_sorting = { git = "https://github.com/keep-starknet-strange/alexandria.git" }

exercises/practice/anagram/src/lib.cairo

@@ -0,0 +1,26 @@
+#[derive(Drop, Debug)]
+struct Set {}
+
+#[generate_trait]
+impl SetImpl of SetTrait {
+    fn new(values: Array<ByteArray>) -> Set {
+        panic!()
+    }
+}
+
+impl SetEq of PartialEq<Set> {
+    fn eq(lhs: @Set, rhs: @Set) -> bool {
+        panic!()
+    }
+
+    fn ne(lhs: @Set, rhs: @Set) -> bool {
+        panic!()
+    }
+}
+
+pub fn anagrams_for(word: @ByteArray, inputs: @Set) -> Set {
+    panic!()
+}
+
+#[cfg(test)]
+mod tests;