[[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]]
true
[[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]]
false
board.length == 9board[i].length == 9board[i][j] 是数字 1-9 或 '.'