How to implement a hash table data structure from scratch?

Question

Aryan Kumar · Answer

Sure. A hash table is a data structure that maps keys to values. The keys are hashed into an array of buckets, and the values are stored in the corresponding bucket. Hash tables are a very efficient data structure for storing and retrieving data, because they can access data in constant time.

Here is an example of how to implement a hash table data structure from scratch in Python:

Python

class HashTable:

    def __init__(self, capacity):
        self.capacity = capacity
        self.table = [None] * capacity

    def hash(self, key):
        return hash(key) % self.capacity

    def insert(self, key, value):
        index = self.hash(key)
        bucket = self.table[index]
        if bucket is None:
            bucket = []
        bucket.append((key, value))
        self.table[index] = bucket

    def get(self, key):
        index = self.hash(key)
        bucket = self.table[index]
        if bucket is None:
            return None
        for k, v in bucket:
            if k == key:
                return v
        return None

Here is an explanation of the code:

The HashTable class has two attributes: capacity and table. The capacity attribute is the number of buckets in the hash table, and the table attribute is a list of buckets.
The hash() method takes a key as input and returns an integer. The integer is the index of the bucket where the key should be stored.
The insert() method takes a key and value as input and inserts the key-value pair into the hash table. The key is hashed into an index, and the key-value pair is stored in the bucket at that index.
The get() method takes a key as input and returns the value associated with that key. The key is hashed into an index, and the value associated with that key is returned.

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How to implement a hash table data structure from scratch?

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