nits (#84)

Co-authored-by: Luke Videckis <lukevideckis@gmail.com>

Author: lrvideckis

src/data_structures/trie.rs

@@ -45,7 +45,7 @@ impl Trie {
     pub fn insert(&mut self, s: &[char]) {
         let mut v = 0;
         for &ch in s {
-            let idx = (ch as u8 - FIRST_CHAR as u8) as usize;
+            let idx = ch as usize - FIRST_CHAR as usize;
             if self.t[v].next[idx].is_none() {
                 self.t[v].next[idx] = Some(self.t.len());
                 self.t.push(Node::default());
@@ -63,11 +63,12 @@ impl Trie {
     pub fn find(&self, s: &[char]) -> usize {
         let mut v = 0;
         for &ch in s {
-            let idx = (ch as u8 - FIRST_CHAR as u8) as usize;
-            if self.t[v].next[idx].is_none() {
+            let idx = ch as usize - FIRST_CHAR as usize;
+            if let Some(u) = self.t[v].next[idx] {
+                v = u;
+            } else {
                 return 0;
             }
-            v = self.t[v].next[idx].unwrap();
         }
         self.t[v].cnt_words
     }