给定n个权值作为n个叶子结点，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)。

-Given the right value as the n-n-leaf node, a binary tree structure, if the minimum weighted path length, saying such a binary tree for the optimal binary tree, also called Huffman tree (Huffman tree).