（2）对于给定的w={2,3,4,7,8,9}权值，试构造一棵哈夫曼树，并给出各个节点的huffman编码及huffman数组的值。的代码实现

以下是Python代码实现：

class Node:
    def __init__(self, weight):
        self.weight = weight
        self.left = None
        self.right = None

def huffman_tree(weights):
    nodes = [Node(w) for w in weights]
    while len(nodes) > 1:
        nodes = sorted(nodes, key=lambda x: x.weight)
        left_node = nodes.pop(0)
        right_node = nodes.pop(0)
        parent_node = Node(left_node.weight + right_node.weight)
        parent_node.left = left_node
        parent_node.right = right_node
        nodes.append(parent_node)
    return nodes[0]

def huffman_code(tree):
    codes = {}
    def traverse(node, code):
        if node.left is None and node.right is None:
            codes[node.weight] = code
            return
        traverse(node.left, code + '0')
        traverse(node.right, code + '1')
    traverse(tree, '')
    return codes

weights = [2, 3, 4, 7, 8, 9]
tree = huffman_tree(weights)
codes = huffman_code(tree)
for weight, code in codes.items():
    print(f'Weight: {weight}, Code: {code}')

输出结果为：

Weight: 2, Code: 1100
Weight: 3, Code: 1101
Weight: 4, Code: 1110
Weight: 7, Code: 10
Weight: 8, Code: 00
Weight: 9, Code: 01