Deletion in Hash Tables using Python

Last Updated : 16 Apr, 2024

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Approach to Deletion in Hash Tables

Hash the Key: Calculate the hash value of the key to determine the index where the key-value pair is stored.
Search for the Key: Traverse the list at the hashed index to find the key-value pair with the given key.
Delete the Key-Value Pair: Once the key is found, remove the key-value pair from the list.

Steps to Implement Deletion in Hash Table in Python

Identify the key you want to delete.
Check if the key exists in the hash table.
If the key exists, use the del keyword to remove the key-value pair from the hash table.
Optionally, handle collision resolution if necessary.
Verify the deletion by inspecting the updated hash table.

Below is the implementation of the approach:

Python

# Creating a hash tablehash_table = {'A': 1, 'B': 2, 'C': 3, 'D': 4}# Deleting an element from the hash tabledelete_key = 'B'if delete_key in hash_table: del hash_table[delete_key] print("Key '{}' deleted successfully.".format(delete_key))else: print("Key '{}' not found in the hash table.".format(delete_key))# Displaying the updated hash tableprint("Updated hash table:", hash_table)

Output

Key 'B' deleted successfully.('Updated hash table:', {'A': 1, 'C': 3, 'D': 4})

In this example, we create a hash table ‘hash_table’ with four key-value pairs. We then delete the key ‘B’ from the hash table using the ‘del’ keyword. Finally, we print the updated hash table to verify the deletion.

Time Complexity: O(1) on average
Auxiliary Space Complexity: O(n)

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