zienyang的专栏

Description DZY loves Fast Fourier Transformation, and he enjoys using it. Fast Fourier Transformation is an algorithm used to calculate convolution. Specifically, if a, b and c are sequences wi

DZY loves colors, and he enjoys painting. On a colorful day, DZY gets a colorful ribbon, which consists of n units (they are numbered from 1 to n from left to right). The color of the i-th unit o

DZY loves Physics, and he enjoys calculating density. Almost everything has density, even a graph. We define the density of a non-directed graph (nodes and edges of the graph have some values) as