From c5e48cf8808a4bacad05d826d26dd5cca962229d Mon Sep 17 00:00:00 2001
From: EFanZh <efanzh@gmail.com>
Date: Thu, 30 Nov 2023 22:45:14 +0800
Subject: [PATCH] Add problem 1975: Maximum Matrix Sum

---
 src/lib.rs                                    |  1 +
 src/problem_1975_maximum_matrix_sum/greedy.rs | 45 +++++++++++++++++++
 src/problem_1975_maximum_matrix_sum/mod.rs    | 24 ++++++++++
 3 files changed, 70 insertions(+)
 create mode 100644 src/problem_1975_maximum_matrix_sum/greedy.rs
 create mode 100644 src/problem_1975_maximum_matrix_sum/mod.rs

diff --git a/src/lib.rs b/src/lib.rs
index 9826b185..343567a1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1371,6 +1371,7 @@ pub mod problem_1967_number_of_strings_that_appear_as_substrings_in_word;
 pub mod problem_1968_array_with_elements_not_equal_to_average_of_neighbors;
 pub mod problem_1971_find_if_path_exists_in_graph;
 pub mod problem_1974_minimum_time_to_type_word_using_special_typewriter;
+pub mod problem_1975_maximum_matrix_sum;
 pub mod problem_1979_find_greatest_common_divisor_of_array;
 
 #[cfg(test)]
diff --git a/src/problem_1975_maximum_matrix_sum/greedy.rs b/src/problem_1975_maximum_matrix_sum/greedy.rs
new file mode 100644
index 00000000..3f41b328
--- /dev/null
+++ b/src/problem_1975_maximum_matrix_sum/greedy.rs
@@ -0,0 +1,45 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn max_matrix_sum(matrix: Vec<Vec<i32>>) -> i64 {
+        let mut candidate_sum = 0_i64;
+        let mut min_abs = i32::MAX;
+        let mut has_odd_negatives = false;
+
+        for row in matrix {
+            for mut value in row {
+                if value < 0 {
+                    value = -value;
+                    has_odd_negatives = !has_odd_negatives;
+                }
+
+                candidate_sum += i64::from(value);
+                min_abs = min_abs.min(value);
+            }
+        }
+
+        if has_odd_negatives {
+            candidate_sum -= i64::from(min_abs) * 2;
+        }
+
+        candidate_sum
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn max_matrix_sum(matrix: Vec<Vec<i32>>) -> i64 {
+        Self::max_matrix_sum(matrix)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}
diff --git a/src/problem_1975_maximum_matrix_sum/mod.rs b/src/problem_1975_maximum_matrix_sum/mod.rs
new file mode 100644
index 00000000..2d6585bc
--- /dev/null
+++ b/src/problem_1975_maximum_matrix_sum/mod.rs
@@ -0,0 +1,24 @@
+pub mod greedy;
+
+pub trait Solution {
+    fn max_matrix_sum(matrix: Vec<Vec<i32>>) -> i64;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+    use crate::test_utilities::Matrix;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (&[[1, -1], [-1, 1]] as &dyn Matrix<_>, 4),
+            (&[[1, 2, 3], [-1, -2, -3], [1, 2, 3]], 16),
+            (&[[-1, 0, -1], [-2, 1, 3], [3, 2, 2]], 15),
+            (&[[2, 9, 3], [5, 4, -4], [1, 7, 1]], 34),
+        ];
+
+        for (matrix, expected) in test_cases {
+            assert_eq!(S::max_matrix_sum(matrix.to_vec()), expected);
+        }
+    }
+}