Add problem 2367: Number of Arithmetic Triplets

src/lib.rs

@@ -1761,6 +1761,7 @@ pub mod problem_2363_merge_similar_items;
 pub mod problem_2364_count_number_of_bad_pairs;
 pub mod problem_2365_task_scheduler_ii;
 pub mod problem_2366_minimum_replacements_to_sort_the_array;
+pub mod problem_2367_number_of_arithmetic_triplets;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2367_number_of_arithmetic_triplets/iterative.rs

@@ -0,0 +1,38 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn arithmetic_triplets(nums: Vec<i32>, diff: i32) -> i32 {
+        let double_diff = diff + diff;
+        let mut seen = [false; 201];
+        let mut result = 0;
+
+        for num in nums {
+            seen[num as u32 as usize] = true;
+
+            result += i32::from(
+                seen.get((num - double_diff) as usize)
+                    .map_or(false, |&first| first && seen[(num - diff) as usize]),
+            );
+        }
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn arithmetic_triplets(nums: Vec<i32>, diff: i32) -> i32 {
+        Self::arithmetic_triplets(nums, diff)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2367_number_of_arithmetic_triplets/mod.rs

@@ -0,0 +1,18 @@
+pub mod iterative;
+
+pub trait Solution {
+    fn arithmetic_triplets(nums: Vec<i32>, diff: i32) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [((&[0, 1, 4, 6, 7, 10] as &[_], 3), 2), ((&[4, 5, 6, 7, 8, 9], 2), 2)];
+
+        for ((nums, diff), expected) in test_cases {
+            assert_eq!(S::arithmetic_triplets(nums.to_vec(), diff), expected);
+        }
+    }
+}