摘要：
题面 There is a company that has N employees(numbered from 1 to N),every employee in the company has a immediate boss (except for the leader of whole co 阅读全文
摘要：
学习set，其他容器每次都要去sort（），除了堆（但其无法lower_bound） 题面 During the War of Resistance Against Japan, tunnel warfare was carried out extensively in the vast areas 阅读全文