This is a standard code library for competitive programming.

Since I'm to lazy, some commonly used and easy-to-write codes are not included, such as Fenwick Tree and Sparse Table.

Because of much personalized, codes that I am very familiar with are also not included, such as the dot product of 2d-vec.

Due to my awful learning ability, many advanced topics are not included, too, such as Dancing Links and K-D Tree.