说明：  C++算法100题余弦函数cos(x)曲线三天打鱼两天晒网阿姆斯特朗数(亦称为自恋性数)等等
(C++ algorithm 100 title cosine function cos (x) curve of a three-day two-day fishing nets drying Armstrong number (also known as the narcissism of a few), etc.)