Just a friendly reminder. Please use English. Some ppl mentioned the language problem before, as LeetCode is an international platform, you are more welcomed to use an international language. :)
And I do not think that is a big problem. As you said, the range of each number is from 1-9. If the algorithm is correct for all the cases of 1-9, it is OK.
虽然过了 但是还是得说 测试数据又有问题 输入 1 13 应该为空，因为题目说了：只能用 1-9！！！
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