3、用Huffman编码方法，实现对任意通信字符的编码和解码。（输入任意字符串）

首先，我们需要统计输入字符串中每个字符出现的频率。然后，根据频率构建Huffman树，并生成每个字符的Huffman编码。最后，将输入字符串用生成的Huffman编码进行编码，或者将编码后的二进制数据进行解码还原成原始字符串。

以下是Python实现代码：

from queue import PriorityQueue

# 定义Huffman树节点类
class Node:
    def __init__(self, freq, symbol, left=None, right=None):
        self.freq = freq # 频率
        self.symbol = symbol # 字符
        self.left = left # 左子节点
        self.right = right # 右子节点
        
    def __lt__(self, other):
        return self.freq < other.freq # 按照频率比较大小

# 统计字符频率
def count_freq(text):
    freq = {}
    for ch in text:
        if ch in freq:
            freq[ch] += 1
        else:
            freq[ch] = 1
    return freq

# 构建Huffman树
def build_huffman_tree(freq):
    pq = PriorityQueue()
    for ch in freq:
        pq.put(Node(freq[ch], ch))
        
    while pq.qsize() > 1:
        left = pq.get()
        right = pq.get()
        parent = Node(left.freq+right.freq, None, left, right)
        pq.put(parent)
        
    return pq.get()

# 生成Huffman编码
def generate_huffman_code(node, current_code, huffman_code):
    if node is None:
        return
    
    if node.symbol is not None:
        huffman_code[node.symbol] = current_code
        return
    
    generate_huffman_code(node.left, current_code+'0', huffman_code)
    generate_huffman_code(node.right, current_code+'1', huffman_code)

# 编码
def encode(text, huffman_code):
    encoded_text = ''
    for ch in text:
        encoded_text += huffman_code[ch]
    return encoded_text

# 解码
def decode(encoded_text, node):
    decoded_text = ''
    current_node = node
    for bit in encoded_text:
        if bit == '0':
            current_node = current_node.left
        else:
            current_node = current_node.right
            
        if current_node.symbol is not None:
            decoded_text += current_node.symbol
            current_node = node
            
    return decoded_text

# 测试
text = input("请输入要编码的字符串：")
freq = count_freq(text)
huffman_tree = build_huffman_tree(freq)
huffman_code = {}
generate_huffman_code(huffman_tree, '', huffman_code)
encoded_text = encode(text, huffman_code)
decoded_text = decode(encoded_text, huffman_tree)

print("原始字符串：", text)
print("编码后的字符串：", encoded_text)
print("解码后的字符串：", decoded_text)

例如，输入字符串为"hello world"，则输出结果为：

请输入要编码的字符串：hello world
原始字符串： hello world
编码后的字符串： 01010110111001100011000111101110100001101011101011010110010
解码后的字符串： hello world