Add problem 3148: Maximum Difference Score in a Grid

Author: EFanZh

src/lib.rs

@@ -2107,6 +2107,7 @@ pub mod problem_3142_check_if_grid_satisfies_conditions;
 pub mod problem_3143_maximum_points_inside_the_square;
 pub mod problem_3146_permutation_difference_between_two_strings;
 pub mod problem_3147_taking_maximum_energy_from_the_mystic_dungeon;
+pub mod problem_3148_maximum_difference_score_in_a_grid;
 pub mod problem_3350_adjacent_increasing_subarrays_detection_ii;
 
 #[cfg(test)]

src/problem_3148_maximum_difference_score_in_a_grid/dynamic_programming.rs

@@ -0,0 +1,46 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn max_score(grid: Vec<Vec<i32>>) -> i32 {
+        let mut grid = grid;
+        let mut iter = grid.iter_mut().map(Vec::as_mut_slice);
+        let cache = iter.next().unwrap();
+
+        let mut result = cache
+            .iter()
+            .fold((i32::MIN, i32::MAX / 2), |(result, min), &value| {
+                (result.max(value - min), min.min(value))
+            })
+            .0;
+
+        iter.for_each(|row| {
+            let mut left = i32::MAX;
+
+            cache.iter_mut().zip(&*row).for_each(|(target, &value)| {
+                result = result.max(value - left.min(*target));
+                *target = (*target).min(value);
+                left = left.min(*target);
+            });
+        });
+
+        result
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn max_score(grid: Vec<Vec<i32>>) -> i32 {
+        Self::max_score(grid)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_3148_maximum_difference_score_in_a_grid/mod.rs

@@ -0,0 +1,26 @@
+pub mod dynamic_programming;
+
+pub trait Solution {
+    fn max_score(grid: Vec<Vec<i32>>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+    use crate::test_utilities::Matrix;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (
+                &[[9, 5, 7, 3], [8, 9, 6, 1], [6, 7, 14, 3], [2, 5, 3, 1]] as &dyn Matrix<_>,
+                9,
+            ),
+            (&[[4, 3, 2], [3, 2, 1]], -1),
+            (&[[4, 9], [5, 2], [3, 1]], 5),
+        ];
+
+        for (grid, expected) in test_cases {
+            assert_eq!(S::max_score(grid.to_vec()), expected);
+        }
+    }
+}