1582. Special Positions in a Binary Matrix: AC

Author: tan-wei

src/solution/mod.rs

@@ -1192,3 +1192,4 @@ mod s1576_replace_all_s_to_avoid_consecutive_repeating_characters;
 mod s1577_number_of_ways_where_square_of_number_is_equal_to_product_of_two_numbers;
 mod s1578_minimum_time_to_make_rope_colorful;
 mod s1579_remove_max_number_of_edges_to_keep_graph_fully_traversable;
+mod s1582_special_positions_in_a_binary_matrix;

src/solution/s1582_special_positions_in_a_binary_matrix.rs

@@ -0,0 +1,93 @@
+/**
+ * [1582] Special Positions in a Binary Matrix
+ *
+ * Given an m x n binary matrix mat, return the number of special positions in mat.
+ * A position (i, j) is called special if mat[i][j] == 1 and all other elements in row i and column j are 0 (rows and columns are 0-indexed).
+ *  
+ * Example 1:
+ * <img alt="" src="https://assets.leetcode.com/uploads/2021/12/23/special1.jpg" style="width: 244px; height: 245px;" />
+ * Input: mat = [[1,0,0],[0,0,1],[1,0,0]]
+ * Output: 1
+ * Explanation: (1, 2) is a special position because mat[1][2] == 1 and all other elements in row 1 and column 2 are 0.
+ *
+ * Example 2:
+ * <img alt="" src="https://assets.leetcode.com/uploads/2021/12/24/special-grid.jpg" style="width: 244px; height: 245px;" />
+ * Input: mat = [[1,0,0],[0,1,0],[0,0,1]]
+ * Output: 3
+ * Explanation: (0, 0), (1, 1) and (2, 2) are special positions.
+ *
+ *  
+ * Constraints:
+ *
+ * 	m == mat.length
+ * 	n == mat[i].length
+ * 	1 <= m, n <= 100
+ * 	mat[i][j] is either 0 or 1.
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/special-positions-in-a-binary-matrix/
+// discuss: https://leetcode.com/problems/special-positions-in-a-binary-matrix/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn num_special(mat: Vec<Vec<i32>>) -> i32 {
+        mat.iter()
+            .enumerate()
+            .fold(
+                (
+                    0,
+                    mat.iter().enumerate().fold(
+                        (vec![0; mat.len()], vec![0; mat[0].len()]),
+                        |(mut row, mut col), (i, v)| {
+                            v.iter()
+                                .enumerate()
+                                .fold((row, col), |(mut row, mut col), (j, &x)| {
+                                    if x == 1 {
+                                        row[i] += 1;
+                                        col[j] += 1;
+                                    }
+                                    (row, col)
+                                })
+                        },
+                    ),
+                ),
+                |(mut c, (row, col)), (i, v)| {
+                    v.iter().enumerate().for_each(|(j, &x)| {
+                        if x == 1 && row[i] == 1 && col[j] == 1 {
+                            c += 1;
+                        }
+                    });
+                    (c, (row, col))
+                },
+            )
+            .0
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1582_example_1() {
+        let mat = vec![vec![1, 0, 0], vec![0, 0, 1], vec![1, 0, 0]];
+
+        let result = 1;
+
+        assert_eq!(Solution::num_special(mat), result);
+    }
+
+    #[test]
+    fn test_1582_example_2() {
+        let mat = vec![vec![1, 0, 0], vec![0, 1, 0], vec![0, 0, 1]];
+
+        let result = 3;
+
+        assert_eq!(Solution::num_special(mat), result);
+    }
+}