Timus Online Judge 2055. Urban Geography 分治,可回溯并查集,
2055.UrbanGeographyTimelimit:2.0secondMemorylimit:128MBAndroidVasyapreparesaprojectinUrbangeography.Theaimoftheprojectistoimprovetheinfrasructureofthecityhelivesin.Nowthecityconsistsof n districts,som