LC36— 有效的数独

输入:
[
  ["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

package com.nie.o3;/* * *@auth wenzhao *@date 2021/3/16 22:38 */

public class LEE036 {
   
    public boolean isValidSudoku(char[][] board) {
   
        //设置成10是为照顾数字9的情况(下标9 数字需要10)
        //第一维 表似行的下标
        boolean[][] row = new boolean[9][10];
        // 第 1 维表示列的下标
        boolean[][] col = new boolean[9][10];
        // 第 1 维表示 board 的下标
        boolean[][] box = new boolean[9][10];
        for (int i = 0; i < 9; i++) {
   
            for (int j = 0; j < 9; j++) {
   
                //验证数字,因此. 跳过
                if (board[i][j] == '.') {
   
                    continue;
                }

                //提取出数字
                int num = board[i][j] - '0';
                //重点:计算机在第几格
                int boardIndex = (i / 3) * 3 + j / 3;

                // 如果发现冲突，直接返回 false
                if (row[i][num] || col[j][num] || box[boardIndex][num]) {
   
                    return false;
                }
                
                //然后占位
                row[i][num] = true;
                col[j][num] = true;
                box[boardIndex][num] = true;
            }
        }
        return true;
    }
}