Styx-ferryman

摘要： Danil decided to earn some money, so he had found a part-time job. The interview have went well, so now he is a light switcher. Danil works in a roote 阅读全文

摘要： Mad scientist Mike has constructed a rooted tree, which consists of n vertices. Each vertex is a reservoir which can be either empty or filled with wa 阅读全文