From 06b3521237ad9a4d1d20d1552e416c0da61e1be9 Mon Sep 17 00:00:00 2001
From: EFanZh <efanzh@gmail.com>
Date: Thu, 19 Oct 2023 22:23:48 +0800
Subject: [PATCH] Add problem 1887: Reduction Operations to Make the Array
 Elements Equal

---
 src/lib.rs                                    |  1 +
 .../iterative.rs                              | 41 +++++++++++++++++++
 .../mod.rs                                    | 18 ++++++++
 3 files changed, 60 insertions(+)
 create mode 100644 src/problem_1887_reduction_operations_to_make_the_array_elements_equal/iterative.rs
 create mode 100644 src/problem_1887_reduction_operations_to_make_the_array_elements_equal/mod.rs

diff --git a/src/lib.rs b/src/lib.rs
index 72543076..6e4fde95 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1451,6 +1451,7 @@ pub mod problem_1880_check_if_word_equals_summation_of_two_words;
 pub mod problem_1881_maximum_value_after_insertion;
 pub mod problem_1884_egg_drop_with_2_eggs_and_n_floors;
 pub mod problem_1886_determine_whether_matrix_can_be_obtained_by_rotation;
+pub mod problem_1887_reduction_operations_to_make_the_array_elements_equal;
 
 #[cfg(test)]
 mod test_utilities;
diff --git a/src/problem_1887_reduction_operations_to_make_the_array_elements_equal/iterative.rs b/src/problem_1887_reduction_operations_to_make_the_array_elements_equal/iterative.rs
new file mode 100644
index 00000000..9a39176c
--- /dev/null
+++ b/src/problem_1887_reduction_operations_to_make_the_array_elements_equal/iterative.rs
@@ -0,0 +1,41 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+use std::cmp::Reverse;
+
+impl Solution {
+    pub fn reduction_operations(nums: Vec<i32>) -> i32 {
+        let mut nums = nums;
+
+        nums.sort_unstable_by_key(|&num| Reverse(num as u32));
+
+        let mut result = 0;
+        let mut prev = 0;
+
+        for (count, num) in (0..).zip(nums) {
+            if num != prev {
+                result += count;
+                prev = num;
+            }
+        }
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn reduction_operations(nums: Vec<i32>) -> i32 {
+        Self::reduction_operations(nums)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}
diff --git a/src/problem_1887_reduction_operations_to_make_the_array_elements_equal/mod.rs b/src/problem_1887_reduction_operations_to_make_the_array_elements_equal/mod.rs
new file mode 100644
index 00000000..8d51a932
--- /dev/null
+++ b/src/problem_1887_reduction_operations_to_make_the_array_elements_equal/mod.rs
@@ -0,0 +1,18 @@
+pub mod iterative;
+
+pub trait Solution {
+    fn reduction_operations(nums: Vec<i32>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [(&[5, 1, 3] as &[_], 3), (&[1, 1, 1], 0), (&[1, 1, 2, 2, 3], 4)];
+
+        for (nums, expected) in test_cases {
+            assert_eq!(S::reduction_operations(nums.to_vec()), expected);
+        }
+    }
+}