摘要： 第二题推出数学公式后发现太坑爹了。。oblem StatementA Ball Triangle is a set of identical balls placed in a triangular shape. A Ball Triangle has N rows, numbered 1 to N from top to bottom. For all i, 1 <= i <= N, the i-th row contains i balls. For example, the following image shows a Ball Triangle with N=3. ... 阅读全文