HDU3986(Harry Potter and the Final Battle)-枚举最短路径+SPFA
HarryPotterandtheFinalBattleDescriptionThefinalbattleiscoming.NowHarryPotterislocatedatcity1,andVoldemortislocatedatcityn.Tomaketheworldpeaceassoonaspossible,Ofcourse,HarryPotterwillchoosetheshortestr