摘要：
You have a total of n coins that you want to form in a staircase shape, where every k-th row must have exactly k coins. Given n, find the total number 阅读全文
摘要：
A self-dividing number is a number that is divisible by every digit it contains. For example, 128 is a self-dividing number because 128 % 1 == 0, 128 阅读全文