Create 2309-greatest-english-letter-in-upper-and-lower-case.rs

Author: memorycancel

2309-greatest-english-letter-in-upper-and-lower-case.rs

@@ -0,0 +1,20 @@
+pub fn greatest_letter(s: String) -> String {
+    use std::collections::HashMap;
+    let mut s_chars = s.chars().collect::<Vec<char>>();
+    s_chars.sort_unstable();
+    s_chars.dedup();
+    let mut mmp = HashMap::new();
+    let mut ret = '0';
+    for c in s_chars {
+        let cu = c.to_ascii_uppercase();
+        let count = mmp.entry(cu).or_insert(0);
+        *count += 1;
+        if *count > 1 && cu > ret { ret = cu }
+    }
+    if ret == '0' { return String::new() }
+    ret.to_string()
+}
+
+fn main() {
+    println!("{:?}", greatest_letter("AbCdEfGhIjK".to_string()));
+}