avoid allocations for results

src/main.rs

@@ -11,7 +11,7 @@ struct App {
 
 impl App {
     /// check if word consists only of letters in query
-    fn check_word(&self, word: &str) -> Option<String> {
+    fn check_word<'a>(&self, word: &'a str) -> Option<&'a str> {
         let mut query = self.query.clone();
         word.chars()
             .try_for_each(|c| {
@@ -19,17 +19,19 @@ impl App {
                 query.remove(position);
                 Some(())
             })
-            .and(Some(word.to_string()))
+            .and(Some(word))
     }
 }
 
 fn main() {
     let app: App = argh::from_env();
 
+    let start = std::time::Instant::now();
     let mut results = WORDS
         .lines()
         .filter_map(|line| app.check_word(line))
-        .collect::<Vec<String>>();
+        .collect::<Vec<&str>>();
+    eprintln!("search took: {:?}", start.elapsed());
 
     results.sort_by(|a, b| {
         a.len()