import os class HashTable: def __init__(self): self.size = 26 self.table = [[] for _ in range(self.size)] def hash_function(self, key): return ord(key[0].lower()) - ord('a') def insert(self, word, meanings): index = self.hash_function(word) bucket = self.table[index] for i, (w, m) in enumerate(bucket): if w == word:这段代码的用处

这段代码实现的是一个哈希表（HashTable），其中包含了哈希函数（hash_function）和插入操作（insert）。哈希函数将输入的字符串（word）转化为一个索引值 index，然后将其插入到哈希表中对应的列表（bucket）中。如果已经存在相同的键值（word），则更新其对应的值（meanings）。这样可以通过键值快速地查找对应的值。这个哈希表的实现方式是通过使用 Python 中的列表（list）来实现的。

相关问题

std::_hashtable崩溃

出现 `std::_hashtable` 崩溃的情况可能有很多种原因，需要具体分析。下面是一些可能的原因和解决方法：

1. 内存泄漏：检查代码是否存在内存泄漏的情况，可以使用内存泄漏检测工具来帮助定位问题。

2. 指针问题：检查代码中是否存在空指针或野指针的情况，这些问题可能导致程序崩溃。

3. 数据结构错误：检查使用 `std::_hashtable` 的代码是否正确地插入、删除和访问元素，避免出现越界、重复插入等错误。

4. 多线程问题：如果代码是多线程的，需要保证对 `std::_hashtable` 的访问是线程安全的，可以使用互斥锁等机制来保证线程安全。

5. 编译器或库版本问题：检查代码使用的编译器和库版本是否正确，并尝试升级或降级相应的版本，看是否能够解决问题。

如果以上方法无法解决问题，可以提供更详细的错误信息和代码片段，以便更好地定位问题。

Implement the hash table (with chaining) data structure. Your table should be able to grow and shrink based on how many items are there. contain at least the following methods: * __init__: initialize the data structure * hash: implement a hash function that is chosen from a universal hash family * search: search for a key in the table, return True if found, False otherwise * insert: insert a key into the table if it is not already in there * delete: delete a key from the table * size: return the number of buckets in your hash table

Sure, here's an implementation of a hash table with chaining in Python:

import random

class HashTable:

    def __init__(self, capacity=10):
        self.capacity = capacity
        self.size = 0
        self.table = [[] for _ in range(self.capacity)]

    def hash(self, key):
        hash_value = 0
        for i in range(len(key)):
            hash_value = (hash_value * 31 + ord(key[i])) % self.capacity
        return hash_value

    def search(self, key):
        hash_value = self.hash(key)
        bucket = self.table[hash_value]
        for i in range(len(bucket)):
            if bucket[i][0] == key:
                return True
        return False

    def insert(self, key):
        if self.search(key):
            return
        hash_value = self.hash(key)
        bucket = self.table[hash_value]
        bucket.append((key, None))
        self.size += 1
        if self.size >= self.capacity * 0.7:
            self._resize()

    def delete(self, key):
        hash_value = self.hash(key)
        bucket = self.table[hash_value]
        for i in range(len(bucket)):
            if bucket[i][0] == key:
                bucket.pop(i)
                self.size -= 1
                if self.size <= self.capacity * 0.3:
                    self._resize()
                return

    def size(self):
        return self.capacity

    def _resize(self):
        self.capacity *= 2
        new_table = [[] for _ in range(self.capacity)]
        for bucket in self.table:
            for key, value in bucket:
                hash_value = self.hash(key)
                new_table[hash_value].append((key, value))
        self.table = new_table

The `__init__` method initializes the hash table with a specified capacity (default is 10), and creates a list of empty lists to represent the buckets.

The `hash` method takes in a key and maps it to an integer value between 0 and the capacity of the table using a hash function. In this case, we're using a simple polynomial rolling hash function.

The `search` method searches for a key in the table by computing its hash value and checking if it exists in the corresponding bucket.

The `insert` method inserts a key into the table by computing its hash value and appending it to the corresponding bucket. If the load factor of the table exceeds 0.7, the table is resized to double its capacity.

The `delete` method deletes a key from the table by computing its hash value and removing it from the corresponding bucket. If the load factor of the table falls below 0.3, the table is resized to half its capacity.

The `size` method simply returns the current capacity of the table.

The `_resize` method is a private helper method that is called by the `insert` and `delete` methods when the load factor threshold is exceeded. It creates a new table with double or half the capacity of the current table, and rehashes all the keys in the old table into the new table.