Add problem 1854: Maximum Population Year

src/lib.rs

@@ -1422,6 +1422,7 @@ pub mod problem_1844_replace_all_digits_with_characters;
 pub mod problem_1845_seat_reservation_manager;
 pub mod problem_1846_maximum_element_after_decreasing_and_rearranging;
 pub mod problem_1848_minimum_distance_to_the_target_element;
+pub mod problem_1854_maximum_population_year;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_1854_maximum_population_year/iterative.rs

@@ -0,0 +1,51 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+use std::convert::TryInto;
+
+impl Solution {
+    pub fn maximum_population(logs: Vec<Vec<i32>>) -> i32 {
+        const MIN_YEAR: usize = 1950;
+
+        let mut diffs = [0_i8; 101];
+
+        for log in logs {
+            let [birth, death]: [_; 2] = log.try_into().ok().unwrap();
+
+            diffs[birth as u32 as usize - MIN_YEAR] += 1;
+            diffs[death as u32 as usize - MIN_YEAR] -= 1;
+        }
+
+        let mut max_population = 0;
+        let mut max_population_year = 0;
+        let mut population = 0;
+
+        for (year, diff) in (MIN_YEAR..).zip(diffs) {
+            population += diff;
+
+            if population > max_population {
+                max_population = population;
+                max_population_year = year;
+            }
+        }
+
+        max_population_year as _
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn maximum_population(logs: Vec<Vec<i32>>) -> i32 {
+        Self::maximum_population(logs)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_1854_maximum_population_year/mod.rs

@@ -0,0 +1,24 @@
+pub mod iterative;
+
+pub trait Solution {
+    fn maximum_population(logs: Vec<Vec<i32>>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (&[[1993, 1999], [2000, 2010]] as &[_], 1993),
+            (&[[1950, 1961], [1960, 1971], [1970, 1981]], 1960),
+        ];
+
+        for (logs, expected) in test_cases {
+            assert_eq!(
+                S::maximum_population(logs.iter().copied().map(Vec::from).collect()),
+                expected
+            );
+        }
+    }
+}