diff --git a/src/string/anagram.rs b/src/string/anagram.rs index b81b7804707..9ea37dc4f6f 100644 --- a/src/string/anagram.rs +++ b/src/string/anagram.rs @@ -1,10 +1,68 @@ -pub fn check_anagram(s: &str, t: &str) -> bool { - sort_string(s) == sort_string(t) +use std::collections::HashMap; + +/// Custom error type representing an invalid character found in the input. +#[derive(Debug, PartialEq)] +pub enum AnagramError { + NonAlphabeticCharacter, } -fn sort_string(s: &str) -> Vec { - let mut res: Vec = s.to_ascii_lowercase().chars().collect::>(); - res.sort_unstable(); +/// Checks if two strings are anagrams, ignoring spaces and case sensitivity. +/// +/// # Arguments +/// +/// * `s` - First input string. +/// * `t` - Second input string. +/// +/// # Returns +/// +/// * `Ok(true)` if the strings are anagrams. +/// * `Ok(false)` if the strings are not anagrams. +/// * `Err(AnagramError)` if either string contains non-alphabetic characters. +pub fn check_anagram(s: &str, t: &str) -> Result { + let s_cleaned = clean_string(s)?; + let t_cleaned = clean_string(t)?; + + Ok(char_count(&s_cleaned) == char_count(&t_cleaned)) +} + +/// Cleans the input string by removing spaces and converting to lowercase. +/// Returns an error if any non-alphabetic character is found. +/// +/// # Arguments +/// +/// * `s` - Input string to clean. +/// +/// # Returns +/// +/// * `Ok(String)` containing the cleaned string (no spaces, lowercase). +/// * `Err(AnagramError)` if the string contains non-alphabetic characters. +fn clean_string(s: &str) -> Result { + s.chars() + .filter(|c| !c.is_whitespace()) + .map(|c| { + if c.is_alphabetic() { + Ok(c.to_ascii_lowercase()) + } else { + Err(AnagramError::NonAlphabeticCharacter) + } + }) + .collect() +} + +/// Computes the histogram of characters in a string. +/// +/// # Arguments +/// +/// * `s` - Input string. +/// +/// # Returns +/// +/// * A `HashMap` where the keys are characters and values are their count. +fn char_count(s: &str) -> HashMap { + let mut res = HashMap::new(); + for c in s.chars() { + *res.entry(c).or_insert(0) += 1; + } res } @@ -12,16 +70,42 @@ fn sort_string(s: &str) -> Vec { mod tests { use super::*; - #[test] - fn test_check_anagram() { - assert!(check_anagram("", "")); - assert!(check_anagram("A", "a")); - assert!(check_anagram("anagram", "nagaram")); - assert!(check_anagram("abcde", "edcba")); - assert!(check_anagram("sIlEnT", "LiStEn")); - - assert!(!check_anagram("", "z")); - assert!(!check_anagram("a", "z")); - assert!(!check_anagram("rat", "car")); + macro_rules! test_cases { + ($($name:ident: $test_case:expr,)*) => { + $( + #[test] + fn $name() { + let (s, t, expected) = $test_case; + assert_eq!(check_anagram(s, t), expected); + assert_eq!(check_anagram(t, s), expected); + } + )* + } + } + + test_cases! { + empty_strings: ("", "", Ok(true)), + empty_and_non_empty: ("", "Ted Morgan", Ok(false)), + single_char_same: ("z", "Z", Ok(true)), + single_char_diff: ("g", "h", Ok(false)), + valid_anagram_lowercase: ("cheater", "teacher", Ok(true)), + valid_anagram_with_spaces: ("madam curie", "radium came", Ok(true)), + valid_anagram_mixed_cases: ("Satan", "Santa", Ok(true)), + valid_anagram_with_spaces_and_mixed_cases: ("Anna Madrigal", "A man and a girl", Ok(true)), + new_york_times: ("New York Times", "monkeys write", Ok(true)), + church_of_scientology: ("Church of Scientology", "rich chosen goofy cult", Ok(true)), + mcdonalds_restaurants: ("McDonald's restaurants", "Uncle Sam's standard rot", Err(AnagramError::NonAlphabeticCharacter)), + coronavirus: ("coronavirus", "carnivorous", Ok(true)), + synonym_evil: ("evil", "vile", Ok(true)), + synonym_gentleman: ("a gentleman", "elegant man", Ok(true)), + antigram: ("restful", "fluster", Ok(true)), + sentences: ("William Shakespeare", "I am a weakish speller", Ok(true)), + part_of_speech_adj_to_verb: ("silent", "listen", Ok(true)), + anagrammatized: ("Anagrams", "Ars magna", Ok(true)), + non_anagram: ("rat", "car", Ok(false)), + invalid_anagram_with_special_char: ("hello!", "world", Err(AnagramError::NonAlphabeticCharacter)), + invalid_anagram_with_numeric_chars: ("test123", "321test", Err(AnagramError::NonAlphabeticCharacter)), + invalid_anagram_with_symbols: ("check@anagram", "check@nagaram", Err(AnagramError::NonAlphabeticCharacter)), + non_anagram_length_mismatch: ("abc", "abcd", Ok(false)), } }