使用递归回溯解决数独问题，简单情况秒杀，复杂情况稍慢些。-solve suduku problem

关于贪心算法的最优安排和稍微复杂的研究，文中给出两个小例子。(About the greedy algorithm is the optimal arrangement and study a little more complicated, two small example is given in the paper.)