first-unique-character-in-a-string

first-unique-character-in-a-string/sol.rs

@@ -0,0 +1,19 @@
+impl Solution {
+    pub fn first_uniq_char(s: String) -> i32 {
+        let (earliest_index, counts) = s.bytes()
+            .enumerate()
+            .fold(([-1; 26], [0; 26]), |(mut earliest_index, mut counts), (idx, chr)| {
+                if earliest_index[chr as usize - 97] == -1 {
+                    earliest_index[chr as usize - 97] = idx as i32;
+                }
+                counts[chr as usize - 97] += 1;
+                (earliest_index, counts)
+            });
+        s.bytes().find_map(|chr| {
+            if counts[chr as usize - 97] == 1 {
+                return Some(earliest_index[chr as usize - 97])
+            }
+            None
+        }).unwrap_or(-1)
+    }
+}