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发帖数: 44 | 1 2. A chess knight is placed on a telephone keypad, arranged as usual ([1,
2,3] [4,5,6] [7,8,9] [*,0,#]). How many valid 10 digit US phone numbers can
be generated by valid movements of the knight? (a valid US phone number is
any 10 digit number not starting with zero or one). |
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