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No Plagiarism!W3XSTs81wAxEJmIyWt3Lposted on PENANA 「庭院深深深幾許,三深不能排一起」有兩種解法。8964 copyright protection396PENANACqpl77AttC 維尼
400Please respect copyright.PENANAhXRjF0ViQk
8964 copyright protection396PENANAAjXsTGFBB8 維尼
一、算「全部排列方式」再扣掉「深深深一起」的組合數8964 copyright protection396PENANA5uc7cPpG2k 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 protection396PENANAWjdNMUd7e4 維尼
*深深深:將「深深深」視為一字元,所以為5!8964 copyright protection396PENANAYS8YYGKB9J 維尼
(7!/3!)-5!=7208964 copyright protection396PENANAc3hblAZ3Cz 維尼
400Please respect copyright.PENANAJV0PNIFC42
8964 copyright protection396PENANAVN4cxSZ9Wt 維尼
二、算「深」各自獨立再加上「兩個深黏一起」的組合數8964 copyright protection396PENANApwHcoGYga6 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 protection396PENANAJ75ucf87zU 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 protection396PENANAsSU92rXiM0 維尼
4!×(5×4×3/3!+5×4)=720400Please respect copyright.PENANAyiKWE9qayB
8964 copyright protection396PENANAmsdoqCJIq6 維尼
15.158.61.22
ns 15.158.61.22da2