[rust] Anagram

1 files changed, 30 insertions, 0 deletions

diff --git a/rust/anagram/src/lib.rs b/rust/anagram/src/lib.rs
new file mode 100644
index 0000000..4602db0
--- /dev/null
+++ b/rust/anagram/src/lib.rs
@@ -0,0 +1,30 @@
+use std::collections::HashSet;
+
+pub fn anagrams_for<'a>(word: &str, possible_anagrams: &[&'a str]) -> HashSet<&'a str> {
+    let word = word.to_lowercase();
+    let word_sign = signature(&word);
+    possible_anagrams.iter().filter(|a| {
+        let a_lower = a.to_lowercase();
+        word_sign == signature(&a_lower) && word != a_lower
+    }).cloned().collect()
+}
+
+/// Compute the signature of a word.
+///
+/// In this case the signature of a word is the ordered list of its lowercased
+/// UTF8 characters.
+fn signature(word: &str) -> Vec<&str> {
+    let mut chars: Vec<&str> = vec![];
+    if !word.is_empty() {
+        let mut start = 0;
+        for i in (start+1)..word.len() {
+            if word.is_char_boundary(i) {
+                chars.push(word.get(start..i).unwrap());
+                start = i;
+            }
+        }
+        chars.push(word.get(start..).unwrap());
+        chars.sort_unstable();
+    }
+    chars
+}