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2325:Persistent Numbers

题目描述
The multiplicative persistence of a number is defined by Neil Sloane (Neil J.A. Sloane in The Persistence of a Number published in Journal of Recreational Mathematics 6, 1973, pp. 97-98., 1973) as the number of steps to reach a one-digit number when repeatedly multiplying the digits. Example:
679 -> 378 -> 168 -> 48 -> 32 -> 6.

That is, the persistence of 679 is 6. The persistence of a single digit number is 0. At the time of this writing it is known that there are numbers with the persistence of 11. It is not known whether there are numbers with the persistence of 12 but it is known that if they exists then the smallest of them would have more than 3000 digits.
The problem that you are to solve here is: what is the smallest number such that the first step of computing its persistence results in the given number?
输入解释
For each test case there is a single line of input containing a decimal number with up to 1000 digits. A line containing -1 follows the last test case.
输出解释
For each test case you are to output one line containing one integer number satisfying the condition stated above or a statement saying that there is no such number in the format shown below.
输入样例
0
1
4
7
18
49
51
768
-1
输出样例
10
11
14
17
29
77
There is no such number.
2688

该题目是Virtual Judge题目,来自 北京大学POJ

源链接: POJ-2325

最后修改于 2020-10-29T06:29:48+00:00 由爬虫自动更新

共提交 0

通过率 --%
时间上限 内存上限
1000 65536