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#389: ucup-team180
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#389: ucup-team2307
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#396: 2147483647str
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#396: 617lyq
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#396: jinqihao2023
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#396: Sktn0089
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#396: ucup-team2172
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法克皮百吨
#396: zdczdc
Accepted: : 246
#402: BigHippo
Accepted: : 245
#403: ucup-team1293
Accepted: : 244
#404: iee
Accepted: : 243
#404: Register
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#404: ucup-team2045
Accepted: : 243
#407: lunchbox
Accepted: : 242
#408: jrjyy
Accepted: : 241
#408: lnw143
Accepted: : 241
what doesn't kill you makes you stronger
#408: std
Accepted: : 241
哼
#411: carrotqq
Accepted: : 239
#411: Nangu
Accepted: : 239
#411: ucup-team267
Accepted: : 239
哈姆。
#411: WJnY
Accepted: : 239
#415: cyq
Accepted: : 236
#415: liyelin
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#417: happybob
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#417: MarSer020
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#417: mln
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#417: ucup-team135
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#417: UESTC_Null_Point_Titans
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#422: ETK
Accepted: : 234
「我是星 我愿投身前途未卜的群星，为梦长明。」
#422: UESTC_lyc_fan_club
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#422: wsxcb
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#422: xmdxmdxmd
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#426: kangleni
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#426: ucup-team4269
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#426: ucup-team7466
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#429: Prime
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#430: 2021cyq
Accepted: : 231
#430: MatrixGroup
Accepted: : 231
どうか どうか どうか | 可是真实的人生，必定是单调、残酷，而缺乏色彩的
#430: moriko
Accepted: : 231
#430: ucup-team3586
Accepted: : 231
#430: ucup-team6748
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#435: binminh01
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#435: LittleDrinks
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#435: ucup-team5008
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#435: ucup-team5984
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#435: ucup-team7557
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喂喂要剃光頭 實學西到此一遊
#441: ucup-team7643
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#441: zhenghanyun
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#443: Calculatelove
Accepted: : 228
Love all my perfect imperfections.
#443: kjhhjki
Accepted: : 228
#443: qzez
Accepted: : 228
对于无向图的情况，基尔霍夫矩阵为 $K=D-A$，其中 $D$ 为度数矩阵，$A$ 为邻接矩阵。树的个数为去掉 $K$ 一行一列的行列式的值。对于外向树，$D$ 为每个点的入边度数和，内向树相反。此时需要去掉根所在行列。BEST 定理：有向欧拉图的欧拉回路个数为：内向树个数乘以 $\prod\limits_{i=1}^{n}deg_i$，其中 $deg_i$ 为 $i$ 号点的度数。
#443: tryandtryagain
Accepted: : 228
#443: ucup-team6454
Accepted: : 228
#443: Wansur
Accepted: : 228
#449: cmll02
Accepted: : 227
#449: heung_min
Accepted: : 227
#449: KnownError_
Accepted: : 227
#449: ucup-team2262
Accepted: : 227
#453: chenshi
Accepted: : 226
#453: feecle6418
Accepted: : 226
gyh ak ioi
#453: ucup-team073
Accepted: : 226
#456: temporary_teamname
Accepted: : 225
#456: ucup-team7796
Accepted: : 225
#456: zzzYheng
Accepted: : 225
你好我的朋友
#459: asdfsdf
Accepted: : 224
#460: 8BQube
Accepted: : 223
#460: cyx
Accepted: : 223
#460: SoyTony
Accepted: : 223
真実はいつもひとつ
#460: ucup-team2819
Accepted: : 223
#460: x_707471
Accepted: : 223
#465: ucup-team7678
Accepted: : 221
#466: Arkweedy
Accepted: : 220
#466: ucup-team7701
Accepted: : 220
#466: xlwang
Accepted: : 220
#469: masterhuang
Accepted: : 219
不要逃避自己的命运
#469: ucup-team4478
Accepted: : 219
#471: ckling
Accepted: : 218
#471: Coffee_zzz
Accepted: : 218
我依然会想你 就像夏花流转四季
#471: do_while_true
Accepted: : 218
#474: alex9801
Accepted: : 217
#474: houzhiyuan
Accepted: : 217
#474: shinonome_ena
Accepted: : 217
#474: ucup-team5656
Accepted: : 217
有点小幽默
#478: fast_photon
Accepted: : 216
#478: rhineofts
Accepted: : 216
#478: SiriYuri
Accepted: : 216
#478: ucup-team6852
Accepted: : 216
#482: gg_gong
Accepted: : 215
Who am I? Why am I here?
#482: infCraft
Accepted: : 215
#482: IvanZhang2009
Accepted: : 215
#482: jxy2012
Accepted: : 215
#482: ucup-team3862
Accepted: : 215
#482: ucup-team870
Accepted: : 215
#488: StefanSebez
Accepted: : 214
#488: ucup-team580
Accepted: : 214
#488: ucup-team7582
Accepted: : 214
#488: ucup-team7733
Accepted: : 214
#492: carboxylBase
Accepted: : 213
#492: Lzy_
Accepted: : 213