摘要：
Stacks of FlapjacksTime limit: 3.000 secondsBackgroundStacks and Queues are often considered the bread and butter of data structures and find use in a... 阅读全文
摘要：
Train SwappingAt an old railway station, you may still encounter one of the last remaining ``train swappers''. A train swapper is an employee of the r... 阅读全文