NOI2015浙江省组队选拔赛试题

ZJOI 2015 Day 1 Hangzhou, China, Jan 29, 2015

Page 1 of 7, revision April 1, 2015

ProblemA. ÔÑiZ

Input le:Output le:Timelimit:Memorylimit:

tree.intree.out6s256MB

b å_ 3 ~k ÔÑaiZ§ 5ù iZ /ãÙ¢ Ø §_ ´U+ L5§ ´Ø oy3 i ûriZ /ã ‰ §±–u_ ú wØL5§ O`ÚO< ã "

3 ã c§_ y3¡ ~Ä +n¯KI )û"

/ã´ ä( § kn¬ /§ù / n 1^‘ >ë å5§¦ zü : mk ^ ´»ò§ ë å5"3iZ¥§_ U3 /þO\½ö~ è"Ó §_ ±3 /þ Ö‰Õ"

XJÖ‰Õ3:uþ§¿…3 /vþkdv ü è§@o_ zUÒ s¤dv·dist(u,v) 7

a5Ö‰ù è"du_ I Ö‰¤k è§Ïd_ o Ò s¤nv=1dv·dist(u,v) “d"Ù¥dist(u,v)L«uÚv3äþ ål( ´» Ú)"

Ï iZ 5½§_ UÀJ / ÖMÕ"3iZ L§¥§_ U¬3, /þ E è§ U¬~ , /þ è§?1 ù ö ± §Ñu²Lþ ħ_ ±£Ä¨ Ö‰Õl a" ´duù iZ /ã¢3 §_ Ã{”´/?1 ` Sü§\U ¨íº

\ ±b½ m©¤k /þÑvk è"

Input

1 1ü ênÚQ©OL«ä :êÚ_ ö ê§Ù¥:l1 nIÒ"

e5n 11§z1n êa,b,c(1≤c≤1000)§L«aÚb mk ^> c >"

e5Q1§z1ü êu,e(0≤|e|≤1000)§L«_ 3:uþ eü è(XJe<0§Ò u´_ 3uþ~ |e|ü è§`x Ò´du←du+e)"êâ y?Û z :þ èêþÑ´ K "

Output

éu_ z ö §ÑÑö ¤± §zU z¤§ =XJ_ ÀJ ` Ö‰:?1Ö‰ s¤"

Constraints

éu15% êâµn≤5000,Q≤2000"

,k10% êâµn≤105,Q≤105§ù ä ( ´ ^ó"

,k5% êâµn≤105,Q≤105§ù ä´‘Å)¤ §)¤ { éuz :i>1§3<i :¥‘Å § I "

,k5% êâµn≤105,Q≤105§ù ä ( ´ i(=ü^óÏL ú : §~f

eã)

"

,k5% êâµn≤105,Q≤105§ù ä ( ´ ±1Ò!: 䧿…IÒ { æ Ó£· & [Ñ o´ ä§ÒØ`² ¤"

,k30% êâµn≤105,Q≤105§_ ¬O\ 裤ke≥0¤",k30% êâµn≤105,Q≤105"

~ Û ´§éu¤kêâ§ù äþ¤k: ÝêÑØ L20§¿…n,Q≥1"

Example

tree.in

10512123124115126127158179111013121813141

01456

tree.out

ProblemB./

Input le:Output le:Timelimit:Memorylimit:

mst.inmst.out1s256MB

b å_ ´ é é ~f§ …¨ ~ ~/kO%§éU < ‰ gCå¤U9 ¯ 5 Ϧ "

ùا â,u) / §¤k ´Ñ ¥ "y3 Ä ?Ö´¦¯4 ÏNX-#ïáå5" kn / §@o ¯ { ,´?En 1^ ´òùn / Ñë å5"

ùn / 5´éÏ § km^>"y3ùm^>du/ 'X§ ÜѤK "z^>Ñk ?E§I s¤ m§1i^>¤I m ei"/ u)± §du_ ´ <)² ´L§ õ ö§¨ â±c ² § zg/ ± §z ei¬´ 0 1 mþ!©Ù ‘Å¢ê"¿…¤keiÑ´ Õá "

y3_ Ñ a?E ´ §¨ ±¦^ Û {§U ÀJI @n 1^>§Ó m©?E§@o?E ¤ mÒ´ùn 1^> ei " ,_ ¬k¦^ \ Û {5* Ñz^> ei §, 2ÀJ ¤ m Y"

_ 3r c§¨ ?E ¤ m Ï"´õ Qº

Input

1 1ü ên,m§L«/ êþÚ> êþ"Ù¥:l1 nIÒ" e5m1§z1ü êa,b§L«:aÚ:b m 5k ^>"ù ãجk->Úg "

Output

1ÑщY§o Ê\ 36 ê"

Constraints

éu15% êâµn≤3"

,k15% êâµn≤10§m=n"

,k10% êâµn≤10§m=n(n 1)/2",k20% êâµn≤5",k20% êâµn≤8",k20% êâµn≤10"

éu¤kêâµm≤n(n 1)/2,n,m≥1"

Example

mst.in

541215435371025145637537162464376

0.6170270.800000

mst.out

Note

(±eSN K¿Ã'§éu)K Ø´7 ")

k

éun [0,1] m ‘ÅCþx1,x2,...,xn§1k @ Ï" ´"

Explanations

éu1 ~§du k4^>§_ w, UÀJù4^§@o‰YÒ´4^> ei¥ ê Ï"§dNote¥ SN§ ‰Y 4=0.8"