First commit

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "rust-bytes-73"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "rust-bytes-73"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

src/main.rs

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+use std::collections::HashMap;
+
+fn main() {
+    println!("{:?}", word_frequency("hello world"));
+}
+
+fn word_frequency(sentence: &str) -> Vec<(String, u32)> {
+    let mut words: Vec<(String, u32)> = sentence
+        .split_whitespace()
+        .map(|x| x.to_lowercase())
+        .map(|x| x.chars().filter(|c| c.is_alphabetic()).collect::<String>())
+        .filter(|x| !x.is_empty())
+        .fold(HashMap::new(), |mut map, word| {
+            map.entry(word)
+                .and_modify(|count| *count += 1)
+                .or_insert(1u32);
+            map
+        })
+        .iter()
+        .map(|(word, count)| (word.clone(), *count))
+        .collect();
+
+    words.sort_by(|(a, _), (b, _)| a.cmp(b));
+
+    words
+}
+
+#[cfg(test)]
+mod test {
+
+    use crate::word_frequency;
+
+    #[test]
+    fn basic_case() {
+        let input = "The quick brown fox, the quick Brown FOX!";
+        let expected = vec![
+            ("brown".to_string(), 2),
+            ("fox".to_string(), 2),
+            ("quick".to_string(), 2),
+            ("the".to_string(), 2),
+        ];
+        assert_eq!(word_frequency(input), expected);
+    }
+
+    #[test]
+    fn empty_string() {
+        let input = "";
+        let expected: Vec<(String, u32)> = vec![];
+        assert_eq!(word_frequency(input), expected);
+    }
+
+    #[test]
+    fn only_punctuation() {
+        let input = ".,!?;:-";
+        let expected: Vec<(String, u32)> = vec![];
+        assert_eq!(word_frequency(input), expected);
+    }
+
+    #[test]
+    fn single_word() {
+        let input = "hello";
+        let expected = vec![("hello".to_string(), 1)];
+        assert_eq!(word_frequency(input), expected);
+    }
+
+    #[test]
+    fn multiple_spaces_and_punctuation() {
+        let input = "hello,,,   world!!!   HELLO.";
+        let expected = vec![("hello".to_string(), 2), ("world".to_string(), 1)];
+        assert_eq!(word_frequency(input), expected);
+    }
+
+    #[test]
+    fn numbers_and_mixed_chars() {
+        let input = "test123 test 123test TEST!";
+        // let expected = vec![("test".to_string(), 3)]; // 3? For sure?
+        let expected = vec![("test".to_string(), 4)];
+        assert_eq!(word_frequency(input), expected);
+    }
+
+    #[test]
+    fn hyphenated_words() {
+        let input = "well-known well-Known WELL-KNOWN";
+        let expected = vec![("wellknown".to_string(), 3)];
+        assert_eq!(word_frequency(input), expected);
+    }
+
+    #[test]
+    fn apostrophes_in_words() {
+        let input = "don't Don'T cant can't";
+        let expected = vec![("cant".to_string(), 2), ("dont".to_string(), 2)];
+        assert_eq!(word_frequency(input), expected);
+    }
+
+    #[test]
+    fn unicode_words() {
+        let input = "café CAFÉ résumé Résumé";
+        let expected = vec![("café".to_string(), 2), ("résumé".to_string(), 2)];
+        assert_eq!(word_frequency(input), expected)
+    }
+}