Add problem 3021: Alice and Bob Playing Flower Game

Author: EFanZh

src/lib.rs

@@ -2050,6 +2050,7 @@ pub mod problem_3012_minimize_length_of_array_using_operations;
 pub mod problem_3014_minimum_number_of_pushes_to_type_word_i;
 pub mod problem_3016_minimum_number_of_pushes_to_type_word_ii;
 pub mod problem_3019_number_of_changing_keys;
+pub mod problem_3021_alice_and_bob_playing_flower_game;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_3021_alice_and_bob_playing_flower_game/mathematical.rs

@@ -0,0 +1,32 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn flower_game(n: i32, m: i32) -> i64 {
+        let n = u64::from(n.cast_unsigned());
+        let m = u64::from(m.cast_unsigned());
+        let even_1 = n / 2;
+        let odd_1 = n - even_1;
+        let even_2 = m / 2;
+        let odd_2 = m - even_2;
+
+        (odd_1 * even_2 + even_1 * odd_2).cast_signed()
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn flower_game(n: i32, m: i32) -> i64 {
+        Self::flower_game(n, m)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_3021_alice_and_bob_playing_flower_game/mod.rs

@@ -0,0 +1,18 @@
+pub mod mathematical;
+
+pub trait Solution {
+    fn flower_game(n: i32, m: i32) -> i64;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [((3, 2), 3), ((1, 1), 0)];
+
+        for ((n, m), expected) in test_cases {
+            assert_eq!(S::flower_game(n, m), expected);
+        }
+    }
+}