LeetCode（34）有效的数独【矩阵】【中等】

在这里插入图片描述

1.题目

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。

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）

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：

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 '.'

2.答案

class Solution {public boolean isValidSudoku(char[][] board) {int[][] block = new int[3][9];int[] line = new int[9];int[] column = new int[9];for (int i = 0; i < 9; i++) {Arrays.fill(line, 0);Arrays.fill(column, 0);if (i % 3 == 0) {for (int j = 0; j < 3; j++) {Arrays.fill(block[j], 0);}}for (int j = 0; j < 9; j++) {// 数字 1-9 在每一行只能出现一次。char lineCar = board[i][j];if ('.' != lineCar) {if (line[lineCar - '0' - 1] != 0) {return false;}line[lineCar - '0' - 1] = 1;}// 数字 1-9 在每一列只能出现一次。char columnChar = board[j][i];if ('.' != columnChar) {if (column[columnChar - '0' - 1] != 0) {return false;}column[columnChar - '0' - 1] = 1;}// 数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。if ('.' != lineCar) {if (block[j / 3][lineCar - '0' - 1] != 0) {return false;}block[j / 3][lineCar - '0' - 1] = 1;}}}return true;}
}