bp神经网络算法。本算法隐含层有一层，节点数可以自行输入，本人测试时一本设置在2-4之间。输入层有两个节点，输出层有一个节点。-BP neural network algorithm.The hidden layer of the algorithm has a layer, the number of nodes can be input, I test a set between 2-4. The input layer has two nodes, and the output layer