信息學(xué)-集訓(xùn)隊(duì)作業(yè)

usaco2001,usopen,greanEarthquake[Chandrasekaran,1977;Tvarozek,AnearthquakehasdestroyedFarmerJohn‘sentirefarm.Beingaresolutefellow,hedecidestorebuildit.AfterrebuildingallNfields(1<=N<=400),herealizeshemustalsoconnectthefieldswithroads.Whencomplete,theremustbesomewaytotraversefromanyfieldtoanyotherfield.Afterstudyingtheterrain,FJhasconcludedthatM(1<=M<=10,000)two-wayroadscanpossiblybebuilt.Sinceheislowonmoney,hewouldliketocompletetheprojectinthechestwaypossible.Asluckwouldhaveit,thecowshaveformedanengineeringconsultingfirmthatspecializesinrebuildingfarmroadsdestroyedinearthquakes.Thecowsalsohaveakeenbusinesssenseandhavenointerestintakingonjobsforwhichtheydonotmakeahandsomeprofit.Thecowsareconcernedabouttheprofitpotential.TheyhavenegotiatedafeeF(1<=F<=2,000,000,000)whichtheyarepaidtorebuildtheroads.Theyaregivenatableofpossibleroads,thetime(inhours)tobuildeachroad(1<=t<=2,000,000,000),andthecosttobuildtheroad(1<=c2,000,000,000).Thetablemightcontainmorethanoneroadconnectingthesamepairoffields.Itwillalwaysbepossibletoconnectallthefieldsgiventheinputdatathoughitmightnotbeprofitable.Determinethehighestprofitratethecowscanmakeinrebuildingthefarm‘sPROBLEMNAME:INPUTLine1:Threeintegers,N,M,andLines2...M+1:Eachlinecontainsfourspace-separatedintegers:i,j,c,andtrespectivelydenotinofieldstheroadconnects,thecost,andthetimerequirementstobuildtheroad.SAMPLEINPUT(filequake.in):5510012205202323OUTPUTAsinglelinecontainingonenumber—printedtofourdecimalplaces—whichisthe umprofitperhourthecowscanachieve.Iftheprofitisnotpositive,print0.0000.SAMPLEOUTPUT(file[Thecowschoosetoconstructthelastfourroads,withatotalcostof83andatimeof16.Theirfeeis100,sotheymakeaprofitof100-83overriodof16timeunits:17/16=1.0625.]一場(chǎng)毀了FarmerJohn的整個(gè)農(nóng)場(chǎng)。他是個(gè)有恒心的人，決定重建農(nóng)場(chǎng)。在重建了所有n（1<=n<=400）塊田野后，他還得修路研究了地形后，F(xiàn)Jm(1<=m<=10000)條雙向的道路可能建造。由于，他希望已盡可能的方式完成整個(gè)工程。幸運(yùn)的是，奶牛們已經(jīng)成立了針對(duì)后修建農(nóng)場(chǎng)道路的工程顧問(wèn)公司。奶牛們也很有經(jīng)濟(jì)頭腦，對(duì)沒(méi)有漂亮利潤(rùn)的工作從不感。奶牛們關(guān)心可能的利益。他們已經(jīng)說(shuō)定了為修路所獲的酬金1<=<=2,000,000,000)，并得到一張關(guān)于可能的道路、修建每條路的時(shí)（以小時(shí)計(jì)（１<=t<=2,000,000,000以及花費(fèi)1<=c<=2000,000,000)確定奶牛修路最高的率輸?shù)谝恍腥齻€(gè)整數(shù)NMF2...M+1行:每行四個(gè)空格隔開(kāi)的整數(shù)i,j,c,t描述兩塊田夜間的一條樣例輸入(filequake.in):5510012201320142015202323輸只