数独解答 优化1：当试值的时候，参考同行、同列和同方阵的其他格子的值。比如其他格子已经填过1、3、4、6、8，那么当前格子只能从2、5、7、8、9中取值。

优化2（已加上）：将0到80转换成对应的横纵坐标是很费时的操作（除法和整除），可以采用表驱动方法，预先存好它们的映射关系，以空间换时间（空间消耗不大，就一个81元素的HashMap）。-Optimization of a Sudoku Answer: When the test value, the reference-friendly, with square columns and with other grid values. Such other grid already filled 1,3,4,6,8, then the current grid can only take values ​ ​ from 2,5,7,8,9. Optimization 2 (already added): The 0-80 converted to the corresponding horizontal and vertical coordinates is very time-consuming operation (division and divisibility), you can use a table-driven approach, pre-stocked their mapping space for time (space consumption is not on a 81 element HashMap).