赫夫曼树：试构造一棵有n个叶子结点的二叉树，每个叶子节点带权为wi，则期中带权路径wpl的最小的二叉树-Huffman Tree: test construct an n-leaf nodes are the binary tree, each leaf node with a right to wi, then the period of the right path with the smallest binary tree wpl

PLC code as a ladder diagram in WPL Software then compiled to Hex and it represents a fully functional 3-floor elevator coding.