Add problem 2870: Minimum Number of Operations to Make Array Empty

Author: EFanZh

src/lib.rs

@@ -1997,6 +1997,7 @@ pub mod problem_2856_minimum_array_length_after_pair_removals;
 pub mod problem_2859_sum_of_values_at_indices_with_k_set_bits;
 pub mod problem_2864_maximum_odd_binary_number;
 pub mod problem_2869_minimum_operations_to_collect_elements;
+pub mod problem_2870_minimum_rounds_to_complete_all_tasks;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2870_minimum_rounds_to_complete_all_tasks/hash_map.rs

@@ -0,0 +1,43 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn min_operations(nums: Vec<i32>) -> i32 {
+        let mut counts = HashMap::<_, u32>::new();
+
+        for num in nums {
+            counts.entry(num).and_modify(|count| *count += 1).or_insert(1);
+        }
+
+        let mut result = 0;
+
+        for &value in counts.values() {
+            if value == 1 {
+                return -1;
+            }
+
+            result += value.div_ceil(3);
+        }
+
+        result as _
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn min_operations(nums: Vec<i32>) -> i32 {
+        Self::min_operations(nums)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2870_minimum_rounds_to_complete_all_tasks/mod.rs

@@ -0,0 +1,18 @@
+pub mod hash_map;
+
+pub trait Solution {
+    fn min_operations(nums: Vec<i32>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [(&[2, 3, 3, 2, 2, 4, 2, 3, 4] as &[_], 4), (&[2, 1, 2, 2, 3, 3], -1)];
+
+        for (nums, expected) in test_cases {
+            assert_eq!(S::min_operations(nums.to_vec()), expected);
+        }
+    }
+}