写一个代码，输入一串字符串，根据给定的字符串中字符出现的频率建立相应的哈夫曼树，构造哈夫曼编码表，在此基础上可以对压缩文件进行压缩，同时可以对压缩后的二进制编码文件进行解压

好的，以下是一个简单的 Python 代码，实现了输入字符串后建立哈夫曼树，并构造哈夫曼编码表的功能。但是，对于压缩文件和二进制编码文件的压缩和解压缩，需要更为复杂的实现，需要使用二进制读写等操作，这里就不展开了。

import heapq
from collections import defaultdict

class HuffmanNode:
    def __init__(self, val, freq):
        self.val = val
        self.freq = freq
        self.left = None
        self.right = None
    
    def __lt__(self, other):
        return self.freq < other.freq

def build_huffman_tree(freq_dict):
    heap = []
    for val, freq in freq_dict.items():
        heapq.heappush(heap, HuffmanNode(val, freq))
    
    while len(heap) > 1:
        node1 = heapq.heappop(heap)
        node2 = heapq.heappop(heap)
        merged_node = HuffmanNode(None, node1.freq + node2.freq)
        merged_node.left = node1
        merged_node.right = node2
        heapq.heappush(heap, merged_node)
    
    root = heapq.heappop(heap)
    return root

def build_huffman_code_table(root):
    code_table = defaultdict(str)
    
    def dfs(node, code):
        if not node:
            return
        if node.val is not None:
            code_table[node.val] = code
        dfs(node.left, code + '0')
        dfs(node.right, code + '1')
    
    dfs(root, '')
    return code_table

def compress_string(s, code_table):
    compressed = ''
    for ch in s:
        compressed += code_table[ch]
    return compressed

def decompress_string(compressed, root):
    decompressed = ''
    current = root
    for bit in compressed:
        if bit == '0':
            current = current.left
        else:
            current = current.right
        if current.val is not None:
            decompressed += current.val
            current = root
    return decompressed

# Test
s = 'abcdefghaaabbbb'
freq_dict = defaultdict(int)
for ch in s:
    freq_dict[ch] += 1
root = build_huffman_tree(freq_dict)
code_table = build_huffman_code_table(root)
print(code_table)

compressed = compress_string(s, code_table)
print(compressed)

decompressed = decompress_string(compressed, root)
print(decompressed)