摘要：
A number that will be the same when it is written forwards or backwards is known as a Palindromic Number. For example, 1234321 is a palindromic number 阅读全文
摘要：
There is a public bike service in Hangzhou City which provides great convenience to the tourists from all over the world. One may rent a bike at any s 阅读全文
摘要：
Suppose a bank has K windows open for service. There is a yellow line in front of the windows which devides the waiting area into two parts. All the c 阅读全文