早年的第3000名到不了USAMO

Here is an AMC 12 problem:

 

 

Tom is delivering mail to the ten houses on one side of the Main Street. He notices the following things: No two adjacent houses both get mail, and at most three houses in a row don't get any mail. How many ways there for this to occur?

所有跟帖： 

• 哈，这个在数学群组贴过。记得贝勒还玩了点小技巧。 -calligraphy- ♂ (0 bytes) () 12/07/2012 postreply 09:05:06

• 回复：早年的第3000名到不了USAMO -混日子了- ♂ (832 bytes) () 12/07/2012 postreply 11:56:35

• 谢谢！答案正确，写了Matlab code验证。 -ca981- ♂ (178218 bytes) () 12/07/2012 postreply 19:11:23