1572. Matrix Diagonal Sum: AC

Author: tan-wei

src/solution/mod.rs

@@ -1184,3 +1184,4 @@ mod s1566_detect_pattern_of_length_m_repeated_k_or_more_times;
 mod s1567_maximum_length_of_subarray_with_positive_product;
 mod s1568_minimum_number_of_days_to_disconnect_island;
 mod s1569_number_of_ways_to_reorder_array_to_get_same_bst;
+mod s1572_matrix_diagonal_sum;

src/solution/s1572_matrix_diagonal_sum.rs

@@ -0,0 +1,93 @@
+/**
+ * [1572] Matrix Diagonal Sum
+ *
+ * Given a square matrix mat, return the sum of the matrix diagonals.
+ * Only include the sum of all the elements on the primary diagonal and all the elements on the secondary diagonal that are not part of the primary diagonal.
+ *  
+ * Example 1:
+ * <img alt="" src="https://assets.leetcode.com/uploads/2020/08/14/sample_1911.png" style="width: 336px; height: 174px;" />
+ * Input: mat = [[1,2,3],
+ *               [4,5,6],
+ *               [7,8,9]]
+ * Output: 25
+ * Explanation: Diagonals sum: 1 + 5 + 9 + 3 + 7 = 25
+ * Notice that element mat[1][1] = 5 is counted only once.
+ *
+ * Example 2:
+ *
+ * Input: mat = [[1,1,1,1],
+ *               [1,1,1,1],
+ *               [1,1,1,1],
+ *               [1,1,1,1]]
+ * Output: 8
+ *
+ * Example 3:
+ *
+ * Input: mat = [[5]]
+ * Output: 5
+ *
+ *  
+ * Constraints:
+ *
+ * 	n == mat.length == mat[i].length
+ * 	1 <= n <= 100
+ * 	1 <= mat[i][j] <= 100
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/matrix-diagonal-sum/
+// discuss: https://leetcode.com/problems/matrix-diagonal-sum/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn diagonal_sum(mat: Vec<Vec<i32>>) -> i32 {
+        mat.iter().enumerate().fold(0, |sum, (i, row)| {
+            sum + row
+                .iter()
+                .enumerate()
+                .filter_map(|(j, n)| (i + j == mat.len() - 1 || i == j).then(|| n))
+                .sum::<i32>()
+        })
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1572_example_1() {
+        let mat = vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9]];
+
+        let result = 25;
+
+        assert_eq!(Solution::diagonal_sum(mat), result);
+    }
+
+    #[test]
+    fn test_1572_example_2() {
+        let mat = vec![
+            vec![1, 1, 1, 1],
+            vec![1, 1, 1, 1],
+            vec![1, 1, 1, 1],
+            vec![1, 1, 1, 1],
+        ];
+
+        let result = 8;
+
+        assert_eq!(Solution::diagonal_sum(mat), result);
+    }
+
+    #[test]
+    fn test_1572_example_3() {
+        let mat = vec![vec![5]];
+
+        let result = 5;
+
+        assert_eq!(Solution::diagonal_sum(mat), result);
+    }
+}