(Exact Cover)[https://en.wikipedia.org/wiki/Exact_cover]
(精確覆蓋問題)[https://baike.baidu.com/item/精確覆蓋問題/15668873?fr=aladdin]
算法：X算法
實現(xiàn)：(Dancing Links)[http://www.cnblogs.com/grenet/p/3145800.html]()
(數(shù)獨解法)[http://www.cnblogs.com/grenet/p/3163550.html]
