面试题~~

famoushz

一家公司 给我出的面试题。。呵呵，蛮简单的。。就是好久没写了。。昨天完成了。有兴趣可以做做。。温故以前知识。
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<span style="">Write a program that can compute the number of unique, valid phone numbers with the following constraints:
<span style="font-family: Times New Roman;">a)       A valid phone number is seven digits in length
<span style="font-family: Times New Roman;">b)       A valid phone number cannot begin with a zero or a one
<span style="font-family: Times New Roman;">c)       A valid phone number can contain only digits
<span style="font-family: Times New Roman;">d)       A valid phone number must consist of a sequence of digits that can be traced by the movements of a chess piece on a normal telephone keypad
 

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