分享一道阿里巴巴（蚂蚁金服）Java笔试题

编写一个函数验证一个给定的9x9 整数矩阵是否符合数独的特性：
a) 每个单元格数字为 1-9
b) 每行的9个数不重复
c) 每列的9个数不重复
d) 如图中分割的9个小3x3矩阵，每个小矩阵里9个数不重复

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|  x  |  x  |  x  |     |     |     |  x  |  x  |  x  |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|  x  |  x  |  x  |     |     |     |  x  |  x  |  x  |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|  x  |  x  |  x  |     |     |     |  x  |  x  |  x  |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|     |     |     |  x  |  x  |  x  |     |     |     |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|     |     |     |  x  |  x  |  x  |     |     |     |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|     |     |     |  x  |  x  |  x  |     |     |     |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|  x  |  x  |  x  |     |     |     |  x  |  x  |  x  |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|  x  |  x  |  x  |     |     |     |  x  |  x  |  x  |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+
|  x  |  x  |  x  |     |     |     |  x  |  x  |  x  |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+