给定n个权值作为n的叶子结点，构造一棵二叉树，若带权路径长度达到最小，称这样的二叉树为最优二叉树，也称为哈夫曼树(Huffman Tree)。哈夫曼树是带权路径长度最短的树，权值较大的结点离根较近。(Given n weights as leaf nodes n, constructing a binary tree. If the right path length to a minimum, said such a binary tree for the optimal binary tree, also known as Huffman tree Huffman tree). Huffman tree is a weighted length of the shortest path tree, nodes with larger weight closer to the root.)