Add problem 1944: Number of Visible People in a Queue

src/lib.rs

@@ -1360,6 +1360,7 @@ pub mod problem_1929_concatenation_of_array;
 pub mod problem_1935_maximum_number_of_words_you_can_type;
 pub mod problem_1936_add_minimum_number_of_rungs;
 pub mod problem_1941_check_if_all_characters_have_equal_number_of_occurrences;
+pub mod problem_1944_number_of_visible_people_in_a_queue;
 pub mod problem_1945_sum_of_digits_of_string_after_convert;
 pub mod problem_1952_three_divisors;
 pub mod problem_1957_delete_characters_to_make_fancy_string;

src/problem_1944_number_of_visible_people_in_a_queue/mod.rs

@@ -0,0 +1,21 @@
+pub mod stack;
+
+pub trait Solution {
+    fn can_see_persons_count(heights: Vec<i32>) -> Vec<i32>;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (&[10, 6, 8, 5, 11, 9] as &[_], &[3, 1, 2, 1, 1, 0] as &[_]),
+            (&[5, 1, 2, 3, 10], &[4, 1, 1, 1, 0]),
+        ];
+
+        for (heights, expected) in test_cases {
+            assert_eq!(S::can_see_persons_count(heights.to_vec()), expected);
+        }
+    }
+}

src/problem_1944_number_of_visible_people_in_a_queue/stack.rs

@@ -0,0 +1,45 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn can_see_persons_count(heights: Vec<i32>) -> Vec<i32> {
+        let mut stack = Vec::new();
+        let mut heights = heights;
+
+        for target in heights.iter_mut().rev() {
+            let mut count = 0;
+
+            while let Some(&top) = stack.last() {
+                count += 1;
+
+                if top < *target {
+                    stack.pop();
+                } else {
+                    break;
+                }
+            }
+
+            stack.push(*target);
+            *target = count;
+        }
+
+        heights
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn can_see_persons_count(heights: Vec<i32>) -> Vec<i32> {
+        Self::can_see_persons_count(heights)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}