Yourcityhas n junctions.Thereare m one-way roadsbetweenthejunctions.Asamayorofthecity,youhavetoensurethesecurityofallthejunctions.Toensurethesecurity,youhavetobuildsomepolicecheckposts.Checkpostscanonlybebuiltinajunction.Acheckpostatjunction icanprotectjunction j ifeither i = j orthepolicepatrolcarcangoto j from i andthencomebackto i.Buildingcheckpostscostssomemoney.Assome...
近期评论