Add problem 2358: Maximum Number of Groups Entering a Competition

src/lib.rs

@@ -1749,6 +1749,7 @@ pub mod problem_2351_first_letter_to_appear_twice;
 pub mod problem_2352_equal_row_and_column_pairs;
 pub mod problem_2353_design_a_food_rating_system;
 pub mod problem_2357_make_array_zero_by_subtracting_equal_amounts;
+pub mod problem_2358_maximum_number_of_groups_entering_a_competition;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2358_maximum_number_of_groups_entering_a_competition/mod.rs

@@ -0,0 +1,18 @@
+pub mod newtons_method;
+
+pub trait Solution {
+    fn maximum_groups(grades: Vec<i32>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [(&[10, 6, 12, 7, 3, 5] as &[_], 3), (&[8, 8], 1)];
+
+        for (grades, expected) in test_cases {
+            assert_eq!(S::maximum_groups(grades.to_vec()), expected);
+        }
+    }
+}

src/problem_2358_maximum_number_of_groups_entering_a_competition/newtons_method.rs

@@ -0,0 +1,37 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn maximum_groups(grades: Vec<i32>) -> i32 {
+        let n = grades.len();
+        let n_times_2 = n * 2;
+        let mut guess = n;
+
+        loop {
+            let new_guess = (guess * guess + n_times_2) / (guess * 2 + 1);
+
+            if new_guess < guess {
+                guess = new_guess;
+            } else {
+                return guess as _;
+            }
+        }
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn maximum_groups(grades: Vec<i32>) -> i32 {
+        Self::maximum_groups(grades)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}