作者scwg ( )
看板PLT
標題Re: [問題] BNF的問題
時間Mon Dec 3 17:01:19 2007
※ 引述《finaldark (......................)》之銘言:
: 有沒有人可以解釋一下,
: 我實在是看不懂,
: 有人可以給個 hint嗎
: 謝謝
: *********************************************************************
: 95年高考-程式設計
BNF:
http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_form
: 二、試寫出一BNF文法,使其產生二進位數字,且數字之值為3之倍數。(20分)
: 答:3倍數之文法如下
: <N3> → <N3>0 | <N1>1 | 0
模三餘零 = 餘零的數 * 2 or 餘一的數 * 2 + 1 or 0
: <N1> → <N2>0 | <N3>1 | 1
模三餘一 = 模三餘二 * 2 or 模三餘零 * 2 + 1 or 1
: <N2> → <N1>0 | <N2>1
模三餘二 = 模三餘一 * 2 or 模三餘二 * 2 + 1
: *********************************************************************
--
And in that line now was a whiskered old man,
with a linen cap and a crooked nose,
who waited in a place called the Stardust Band Shell
to share his part of the secret of heaven:
that each affects the other and the other affects the next,
and the world is full of stories, but the stories are all one.
--
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1F:推 finaldark:謝謝 我懂了 :P 12/04 15:20