哈夫曼树，第一行输入一个数n，表示叶结点的个数。 需要用这些叶结点生成哈夫曼树，根据哈夫曼树的概念，这些结点有权值，即weight，题目需要输出哈夫曼树的带权路径长度（WPL）。

好的，我来给出一个实现。首先，我们需要定义一个节点类来表示哈夫曼树中的节点，包含权值和左右子节点。代码如下：

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

接着，我们需要构建哈夫曼树。我们可以通过一个优先队列来实现，每次取出权值最小的两个节点，合并成一个新节点，并将其放回优先队列中，直到只剩下一个节点。代码如下：

import heapq

def build_huffman_tree(weights):
    """
    Build a Huffman tree from a list of weights.
    """
    nodes = [HuffmanNode(weight) for weight in weights]
    heapq.heapify(nodes)
    
    while len(nodes) > 1:
        left = heapq.heappop(nodes)
        right = heapq.heappop(nodes)
        parent = HuffmanNode(left.weight + right.weight, left, right)
        heapq.heappush(nodes, parent)
    
    return nodes[0]

最后，我们需要计算哈夫曼树的带权路径长度。遍历树的所有叶子节点，将每个叶子节点的权值乘以其到根节点的距离，然后将所有结果相加即可。代码如下：

def huffman_wpl(root, depth=0):
    """
    Calculate the WPL of a Huffman tree.
    """
    if not root:
        return 0
    
    if not root.left and not root.right:
        return root.weight * depth
    
    return huffman_wpl(root.left, depth+1) + huffman_wpl(root.right, depth+1)

完整代码如下：

import heapq

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

def build_huffman_tree(weights):
    """
    Build a Huffman tree from a list of weights.
    """
    nodes = [HuffmanNode(weight) for weight in weights]
    heapq.heapify(nodes)
    
    while len(nodes) > 1:
        left = heapq.heappop(nodes)
        right = heapq.heappop(nodes)
        parent = HuffmanNode(left.weight + right.weight, left, right)
        heapq.heappush(nodes, parent)
    
    return nodes[0]

def huffman_wpl(root, depth=0):
    """
    Calculate the WPL of a Huffman tree.
    """
    if not root:
        return 0
    
    if not root.left and not root.right:
        return root.weight * depth
    
    return huffman_wpl(root.left, depth+1) + huffman_wpl(root.right, depth+1)

n = int(input())
weights = list(map(int, input().split()))

root = build_huffman_tree(weights)
wpl = huffman_wpl(root)

print(wpl)

这样，我们就可以输入叶子节点个数和权值，输出哈夫曼树的带权路径长度了。