solve 36

Author: Zhang Xiaodong

src/solution/mod.rs

@@ -31,3 +31,4 @@ mod s0032_longest_valid_parentheses;
 mod s0033_search_in_rotated_sorted_array;
 mod s0034_find_first_and_last_position_of_element_in_sorted_array;
 mod s0035_search_insert_position;
+mod s0036_valid_sudoku;

src/solution/s0036_valid_sudoku.rs

@@ -0,0 +1,149 @@
+/**
+ * [36] 有效的数独
+ *
+ * 请你判断一个 9 x 9 的数独是否有效。只需要 根据以下规则 ，验证已经填入的数字是否有效即可。
+ * <ol>
+ * 	数字 1-9 在每一行只能出现一次。
+ * 	数字 1-9 在每一列只能出现一次。
+ * 	数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。（请参考示例图）
+ * </ol>
+ *  
+ * 注意：
+ *
+ * 	一个有效的数独（部分已被填充）不一定是可解的。
+ * 	只需要根据以上规则，验证已经填入的数字是否有效即可。
+ * 	空白格用 '.' 表示。
+ *
+ *  
+ * 示例 1：
+ * <img src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2021/04/12/250px-sudoku-by-l2g-20050714svg.png" style="height:250px; width:250px" />
+ * 输入：board =
+ * [["5","3",".",".","7",".",".",".","."]
+ * ,["6",".",".","1","9","5",".",".","."]
+ * ,[".","9","8",".",".",".",".","6","."]
+ * ,["8",".",".",".","6",".",".",".","3"]
+ * ,["4",".",".","8",".","3",".",".","1"]
+ * ,["7",".",".",".","2",".",".",".","6"]
+ * ,[".","6",".",".",".",".","2","8","."]
+ * ,[".",".",".","4","1","9",".",".","5"]
+ * ,[".",".",".",".","8",".",".","7","9"]]
+ * 输出：true
+ *
+ * 示例 2：
+ *
+ * 输入：board =
+ * [["8","3",".",".","7",".",".",".","."]
+ * ,["6",".",".","1","9","5",".",".","."]
+ * ,[".","9","8",".",".",".",".","6","."]
+ * ,["8",".",".",".","6",".",".",".","3"]
+ * ,["4",".",".","8",".","3",".",".","1"]
+ * ,["7",".",".",".","2",".",".",".","6"]
+ * ,[".","6",".",".",".",".","2","8","."]
+ * ,[".",".",".","4","1","9",".",".","5"]
+ * ,[".",".",".",".","8",".",".","7","9"]]
+ * 输出：false
+ * 解释：除了第一行的第一个数字从 5 改为 8 以外，空格内其他数字均与 示例1 相同。 但由于位于左上角的 3x3 宫内有两个 8 存在, 因此这个数独是无效的。
+ *  
+ * 提示：
+ *
+ * 	board.length == 9
+ * 	board[i].length == 9
+ * 	board[i][j] 是一位数字（1-9）或者 '.'
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.cn/problems/valid-sudoku/
+// discuss: https://leetcode.cn/problems/valid-sudoku/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn is_valid_sudoku(board: Vec<Vec<char>>) -> bool {
+        for row in &board {
+            let mut exists = vec![0u8; 10];
+            for c in row {
+                if *c != '.' {
+                    let c = *c as usize - '0' as usize;
+                    if exists[c] > 0 {
+                        return false;
+                    }
+                    exists[c] = 1;
+                }
+            }
+        }
+
+        for col in (0..9) {
+            let mut exists = vec![0u8; 10];
+            for i in (0..9) {
+                let c = &board[i][col];
+                if *c != '.' {
+                    let c = *c as usize - '0' as usize;
+                    if exists[c] > 0 {
+                        return false;
+                    }
+                    exists[c] = 1;
+                }
+            }
+        }
+
+        for i in (0..9).step_by(3) {
+            for j in (0..9).step_by(3) {
+                let mut exists = vec![0u8; 10];
+                for m in (i..i + 3) {
+                    for n in (j..j + 3) {
+                        let c = board[m][n];
+                        if c == '.' {
+                            continue;
+                        }
+                        let c = c as usize - '0' as usize;
+                        if exists[c] > 0 {
+                            return false;
+                        }
+                        exists[c] = 1;
+                    }
+                }
+            }
+        }
+        true
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_36() {
+        assert_eq!(
+            Solution::is_valid_sudoku(vec![
+                vec!['5', '3', '.', '.', '7', '.', '.', '.', '.'],
+                vec!['6', '.', '.', '1', '9', '5', '.', '.', '.'],
+                vec!['.', '9', '8', '.', '.', '.', '.', '6', '.'],
+                vec!['8', '.', '.', '.', '6', '.', '.', '.', '3'],
+                vec!['4', '.', '.', '8', '.', '3', '.', '.', '1'],
+                vec!['7', '.', '.', '.', '2', '.', '.', '.', '6'],
+                vec!['.', '6', '.', '.', '.', '.', '2', '8', '.'],
+                vec!['.', '.', '.', '4', '1', '9', '.', '.', '5'],
+                vec!['.', '.', '.', '.', '8', '.', '.', '7', '9'],
+            ]),
+            true
+        );
+        assert_eq!(
+            Solution::is_valid_sudoku(vec![
+                vec!['8', '3', '.', '.', '7', '.', '.', '.', '9'],
+                vec!['6', '.', '.', '1', '9', '5', '.', '.', '.'],
+                vec!['.', '9', '8', '.', '.', '.', '.', '6', '.'],
+                vec!['8', '.', '.', '.', '6', '.', '.', '.', '3'],
+                vec!['4', '.', '.', '8', '.', '3', '.', '.', '1'],
+                vec!['7', '.', '.', '.', '2', '.', '.', '.', '6'],
+                vec!['.', '6', '.', '.', '.', '.', '2', '8', '.'],
+                vec!['.', '.', '.', '4', '1', '9', '.', '.', '5'],
+                vec!['.', '.', '.', '.', '8', '.', '.', '7', '9'],
+            ]),
+            false
+        );
+    }
+}