哈夫曼哈夫曼编/译码器

哈夫曼编码是一种可变长度编码，它将出现频率较高的字符用较短的编码表示，出现频率较低的字符用较长的编码表示，从而达到压缩数据的目的。哈夫曼编码的编码和解码过程都需要用到哈夫曼树，因此需要先构建哈夫曼树。

下面是一个Python实现的哈夫曼编/译码器的例子：

import heapq
from collections import defaultdict

# 构建哈夫曼树
def build_huffman_tree(freq_dict):
    heap = [[freq, [char, ""]] for char, freq in freq_dict.items()]
    heapq.heapify(heap)
    while len(heap) > 1:
        left = heapq.heappop(heap)
        right = heapq.heappop(heap)
        for pair in left[1:]:
            pair[1] = '0' + pair[1]
        for pair in right[1:]:
            pair[1] = '1' + pair[1]
        heapq.heappush(heap, [left[0] + right[0]] + left[1:] + right[1:])
    return sorted(heapq.heappop(heap)[1:], key=lambda x: (len(x[-1]), x))

# 编码
def encode(text):
    freq_dict = defaultdict(int)
    for char in text:
        freq_dict[char] += 1
    huffman_tree = build_huffman_tree(freq_dict)
    code_dict = dict(huffman_tree)
    encoded_text = ''.join([code_dict[char] for char in text])
    return encoded_text, code_dict

# 解码
def decode(encoded_text, code_dict):
    decoded_text = ''
    code = ''
    for bit in encoded_text:
        code += bit
        if code in code_dict:
            decoded_text += code_dict[code]
            code = ''
    return decoded_text