摘要：Given any string of N (≥5) characters, you are asked to form the characters into the shape of U. For example, helloworld can be printed as: h d e l l 阅读全文

摘要：People in Mars represent the colors in their computers in a similar way as the Earth people. That is, a color is represented by a 6-digit number, wher 阅读全文

摘要：Notice that the number 123456789 is a 9-digit number consisting exactly the numbers from 1 to 9, with no duplication. Double it we will obtain 2469135 阅读全文

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