Python中如何实现Rabin-Karp算法？

def rabin_karp(text, pattern):
    prime = 101  # 选择一个素数作为哈希的基数
    base = 256  # 字符集大小，这里假设是ASCII

    # 计算模式字符串的哈希值
    pattern_hash = 0
    for char in pattern:
        pattern_hash = (pattern_hash * base + ord(char)) % prime

    # 计算文本字符串的第一个窗口的哈希值
    text_hash = 0
    for i in range(len(pattern)):
        text_hash = (text_hash * base + ord(text[i])) % prime

    # 滑动窗口匹配
    for i in range(len(text) - len(pattern) + 1):
        if pattern_hash == text_hash:
            # 如果哈希值相同，进行字符级别的比较
            if text[i:i+len(pattern)] == pattern:
                return i  # 返回匹配的起始位置

        # 计算下一个窗口的哈希值
        if i < len(text) - len(pattern):
            text_hash = (text_hash * base - ord(text[i]) * pow(base, len(pattern), prime) + ord(text[i + len(pattern)])) % prime
            text_hash = (text_hash + prime) % prime  # 确保哈希值为正

    return -1  # 如果没有找到匹配，返回-1

# 测试 Rabin-Karp 算法
text = "AABAACAADAABAAABAA"
pattern = "AABA"
result = rabin_karp(text, pattern)
print(f"Pattern found at index: {result}")  # 输出: Pattern found at index: 0