Add problem 2306: Naming a Company

src/lib.rs

@@ -1717,6 +1717,7 @@ pub mod problem_2302_count_subarrays_with_score_less_than_k;
 pub mod problem_2303_calculate_amount_paid_in_taxes;
 pub mod problem_2304_minimum_path_cost_in_a_grid;
 pub mod problem_2305_fair_distribution_of_cookies;
+pub mod problem_2306_naming_a_company;
 pub mod problem_2309_greatest_english_letter_in_upper_and_lower_case;
 pub mod problem_2310_sum_of_numbers_with_units_digit_k;
 pub mod problem_2315_count_asterisks;

src/problem_2306_naming_a_company/group_by_prefix.rs

@@ -0,0 +1,50 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+use std::collections::HashSet;
+
+impl Solution {
+    pub fn distinct_names(ideas: Vec<String>) -> i64 {
+        let mut groups = [(); 26].map(|()| HashSet::<u64>::new());
+
+        for idea in ideas {
+            let mut iter = idea.bytes();
+            let prefix = usize::from(iter.next().unwrap());
+            let suffix = iter.fold(0, |result, c| (result << 7) | u64::from(c));
+
+            groups[prefix - usize::from(b'a')].insert(suffix);
+        }
+
+        let mut result = 0;
+        let mut iter = groups.iter();
+
+        while let Some(left) = iter.next() {
+            if !left.is_empty() {
+                iter.clone().for_each(|right| {
+                    let intersections = left.intersection(right).count();
+
+                    result += (left.len() - intersections) * (right.len() - intersections);
+                });
+            }
+        }
+
+        (result * 2) as _
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn distinct_names(ideas: Vec<String>) -> i64 {
+        Self::distinct_names(ideas)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2306_naming_a_company/mod.rs

@@ -0,0 +1,24 @@
+pub mod group_by_prefix;
+
+pub trait Solution {
+    fn distinct_names(ideas: Vec<String>) -> i64;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (&["coffee", "donuts", "time", "toffee"] as &[_], 6),
+            (&["lack", "back"], 0),
+        ];
+
+        for (ideas, expected) in test_cases {
+            assert_eq!(
+                S::distinct_names(ideas.iter().copied().map(str::to_string).collect()),
+                expected,
+            );
+        }
+    }
+}