Add problem 2012: Sum of Beauty in the Array

src/lib.rs

@@ -1392,6 +1392,7 @@ pub mod problem_2000_reverse_prefix_of_word;
 pub mod problem_2006_count_number_of_pairs_with_absolute_difference_k;
 pub mod problem_2007_find_original_array_from_doubled_array;
 pub mod problem_2011_final_value_of_variable_after_performing_operations;
+pub mod problem_2012_sum_of_beauty_in_the_array;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2012_sum_of_beauty_in_the_array/iterative.rs

@@ -0,0 +1,58 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn sum_of_beauties(nums: Vec<i32>) -> i32 {
+        let iter_1 = nums.iter().copied();
+        let mut iter_2 = iter_1.clone();
+
+        iter_2.next();
+
+        let mut iter_3 = iter_2.clone();
+
+        iter_3.next();
+
+        // Calculate right maxes.
+
+        let mut right_mins = vec![0; nums.len() - 2];
+        let mut right_min = i32::MAX;
+
+        for (target, num) in right_mins.iter_mut().zip(iter_3.clone()).rev() {
+            right_min = right_min.min(num);
+            *target = right_min;
+        }
+
+        let mut result = 0;
+
+        let mut left_max = i32::MIN;
+
+        for (((left, middle), right), right_min) in iter_1.zip(iter_2).zip(iter_3).zip(right_mins) {
+            left_max = left_max.max(left);
+
+            if left_max < middle && middle < right_min {
+                result += 2;
+            } else if left < middle && middle < right {
+                result += 1;
+            }
+        }
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn sum_of_beauties(nums: Vec<i32>) -> i32 {
+        Self::sum_of_beauties(nums)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2012_sum_of_beauty_in_the_array/mod.rs

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