Add problem 2053: Kth Distinct String in an Array

src/lib.rs

@@ -1408,6 +1408,7 @@ pub mod problem_2038_remove_colored_pieces_if_both_neighbors_are_the_same_color;
 pub mod problem_2042_check_if_numbers_are_ascending_in_a_sentence;
 pub mod problem_2043_simple_bank_system;
 pub mod problem_2047_number_of_valid_words_in_a_sentence;
+pub mod problem_2053_kth_distinct_string_in_an_array;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2053_kth_distinct_string_in_an_array/hash_map.rs

@@ -0,0 +1,36 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn kth_distinct(arr: Vec<String>, k: i32) -> String {
+        let mut counts = HashMap::<_, u16>::new();
+
+        for s in &arr {
+            counts.entry(s.as_str()).and_modify(|count| *count += 1).or_insert(1);
+        }
+
+        arr.iter()
+            .filter(|&s| counts[s.as_str()] == 1)
+            .nth(k as u32 as usize - 1)
+            .map_or_else(String::new, String::clone)
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn kth_distinct(arr: Vec<String>, k: i32) -> String {
+        Self::kth_distinct(arr, k)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2053_kth_distinct_string_in_an_array/mod.rs

@@ -0,0 +1,25 @@
+pub mod hash_map;
+
+pub trait Solution {
+    fn kth_distinct(arr: Vec<String>, k: i32) -> String;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            ((&["d", "b", "c", "b", "c", "a"] as &[_], 2), "a"),
+            ((&["aaa", "aa", "a"], 1), "aaa"),
+            ((&["a", "b", "a"], 3), ""),
+        ];
+
+        for ((arr, k), expected) in test_cases {
+            assert_eq!(
+                S::kth_distinct(arr.iter().copied().map(str::to_string).collect(), k),
+                expected,
+            );
+        }
+    }
+}