摘要： Kyle is a student of Programming Monkey Elementary School. Just as others, he is deeply concerned with his grades. Last month, the school held an exam 阅读全文

摘要： 描述 一条单向的铁路线上,依次有编号为 1, 2, ..., n 的 n 个火车站。每个火车站都有一个级别,最低为 1 级。现有若干趟车次在这条线路上行驶,每一趟都满足如下要求:如果这趟车次停靠了火车站 x,则始发站、终点站之间所有级别大于等于火车站 x 的都必须停靠。(注意:起始站和终点站自然也算 阅读全文