九宫问题：实现3*3的方格中填1-9的数，使其横，竖，叉的三个数之和为15；求解共有几种填写方法。原创vc实现。-Nine-palace issues: the achievement of the 3* 3 grid to fill a number of 1-9 to make it horizontal, vertical, fork and three the number of 15 Solving fill a total of several methods. Original