Add problem 2679: Sum in a Matrix

Author: EFanZh

src/lib.rs

@@ -1938,6 +1938,7 @@ pub mod problem_2670_find_the_distinct_difference_array;
 pub mod problem_2671_frequency_tracker;
 pub mod problem_2673_make_costs_of_paths_equal_in_a_binary_tree;
 pub mod problem_2678_number_of_senior_citizens;
+pub mod problem_2679_sum_in_a_matrix;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2679_sum_in_a_matrix/iterative.rs

@@ -0,0 +1,37 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn matrix_sum(nums: Vec<Vec<i32>>) -> i32 {
+        let mut nums = nums;
+
+        for num in &mut nums {
+            num.sort_unstable_by(|&lhs, &rhs| u32::cmp(&(rhs as _), &(lhs as _)));
+        }
+
+        (0..nums.first().map_or(0, Vec::len))
+            .map(|column| {
+                nums.iter()
+                    .map_while(|row| row.get(column).copied())
+                    .fold(0, |max, value| u32::max(max, value as _))
+            })
+            .sum::<u32>() as _
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn matrix_sum(nums: Vec<Vec<i32>>) -> i32 {
+        Self::matrix_sum(nums)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2679_sum_in_a_matrix/mod.rs

@@ -0,0 +1,22 @@
+pub mod iterative;
+
+pub trait Solution {
+    fn matrix_sum(nums: Vec<Vec<i32>>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+    use crate::test_utilities::Matrix;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (&[[7, 2, 1], [6, 4, 2], [6, 5, 3], [3, 2, 1]] as &dyn Matrix<_>, 15),
+            (&[[1]], 1),
+        ];
+
+        for (nums, expected) in test_cases {
+            assert_eq!(S::matrix_sum(nums.to_vec()), expected);
+        }
+    }
+}