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No Plagiarism!xSB9OSVUZZM7b7IJ932Aposted on PENANA 「庭院深深深幾許,三深不能排一起」有兩種解法。8964 copyright protection445PENANAibuN1PEMWY 維尼
449Please respect copyright.PENANAEwAQlLhhJv
8964 copyright protection445PENANAoCcthhevjk 維尼
一、算「全部排列方式」再扣掉「深深深一起」的組合數8964 copyright protection445PENANAU7vOfNJ4aX 維尼
*全部:有七個字元,所以為7!,但因「深」可互相調換,需再除以3!8964 copyright protection445PENANAeTKS52xfFq 維尼
*深深深:將「深深深」視為一字元,所以為5!8964 copyright protection445PENANADjkdXnBTIS 維尼
(7!/3!)-5!=7208964 copyright protection445PENANAF58zunAAkn 維尼
449Please respect copyright.PENANACG5jDFwyi0
8964 copyright protection445PENANA6ZdgDlFkio 維尼
二、算「深」各自獨立再加上「兩個深黏一起」的組合數8964 copyright protection445PENANA0LOYqYLiQz 維尼
*「深」獨立:其餘四字排列為4!,有五個位置給「深」安插,所以為(5×4×3),但因「深」可互相調換,需再除以3!8964 copyright protection445PENANAvEen3G5NhX 維尼
*兩深一起:其餘四字排列為4!,將「深深」視為一字元安插,一樣五個位置,所以為(5×4)8964 copyright protection445PENANAIRMfSFGlW6 維尼
4!×(5×4×3/3!+5×4)=720449Please respect copyright.PENANAs5HGRBQ5O8
8964 copyright protection445PENANAKoZTlXXpRh 維尼
3.144.109.104
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