Add problem 2144: Minimum Cost of Buying Candies With Discount

src/lib.rs

@@ -1457,6 +1457,7 @@ pub mod problem_2130_maximum_twin_sum_of_a_linked_list;
 pub mod problem_2134_minimum_swaps_to_group_all_1s_together_ii;
 pub mod problem_2138_divide_a_string_into_groups_of_size_k;
 pub mod problem_2140_solving_questions_with_brainpower;
+pub mod problem_2144_minimum_cost_of_buying_candies_with_discount;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2144_minimum_cost_of_buying_candies_with_discount/greedy.rs

@@ -0,0 +1,38 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn minimum_cost(cost: Vec<i32>) -> i32 {
+        let mut cost = cost;
+
+        cost.sort_unstable_by(|lhs, rhs| rhs.cmp(lhs));
+
+        let mut result = 0;
+        let mut iter = cost.chunks_exact(3);
+
+        for chunk in iter.by_ref() {
+            result += chunk[0] + chunk[1];
+        }
+
+        result += iter.remainder().iter().sum::<i32>();
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn minimum_cost(cost: Vec<i32>) -> i32 {
+        Self::minimum_cost(cost)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2144_minimum_cost_of_buying_candies_with_discount/greedy_2.rs

@@ -0,0 +1,37 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn minimum_cost(cost: Vec<i32>) -> i32 {
+        let mut cost = cost;
+
+        cost.sort_unstable_by(|lhs, rhs| rhs.cmp(lhs));
+
+        let mut result = cost.iter().sum::<i32>();
+
+        if let Some(cost) = cost.get(2..) {
+            for num in cost.iter().step_by(3) {
+                result -= num;
+            }
+        }
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn minimum_cost(cost: Vec<i32>) -> i32 {
+        Self::minimum_cost(cost)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2144_minimum_cost_of_buying_candies_with_discount/mod.rs

@@ -0,0 +1,25 @@
+pub mod greedy;
+pub mod greedy_2;
+
+pub trait Solution {
+    fn minimum_cost(cost: Vec<i32>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (&[1, 2, 3] as &[_], 5),
+            (&[6, 5, 7, 9, 2, 2], 23),
+            (&[5, 5], 10),
+            (&[3, 3, 3, 1], 7),
+            (&[1], 1),
+        ];
+
+        for (cost, expected) in test_cases {
+            assert_eq!(S::minimum_cost(cost.to_vec()), expected);
+        }
+    }
+}