BA

代码说明：

说明：  复杂网络经典BA模型以及两个改进的BA模型，分别封装成函数。输入参数有：网络节点个数，初始节点个数，新店与就网络连边的数目，初始网络边的连接(Complex network classic BA model and two improved BA model, are encapsulated into a function. Input parameters: the number of network nodes, the initial number of nodes, the new store on the edge of the network even number side of the initial network connection)