HashMap Implementation from Scratch in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the hash map with empty buckets.

DSA Python

class HashMap:
    def __init__(self, size=10):
        self.size = size
        self.buckets = [1]

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A[0] * self.size

Blist(range(self.size))

C{}

D[[] for _ in range(self.size)]

Attempts:

3 left

💡 Hint

Common Mistakes

Using a list of zeros instead of empty lists.

Using a dictionary instead of a list of buckets.

We create a list of empty lists, one for each bucket, to store key-value pairs.

2fill in blank

medium

Complete the code to compute the bucket index using the built-in hash function.

DSA Python

def _get_bucket_index(self, key):
    return [1] % self.size

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Akey

Bhash(key)

Clen(key)

Dkey % self.size

Attempts:

3 left

💡 Hint

Common Mistakes

Using the key directly without hashing.

Using length of key which is not unique.

We use the built-in hash function to get a hash value for the key, then mod by size to find the bucket.

3fill in blank

hard

Fix the error in the put method to update the value if the key already exists.

DSA Python

def put(self, key, value):
    index = self._get_bucket_index(key)
    bucket = self.buckets[index]
    for i, (k, v) in enumerate(bucket):
        if k == key:
            bucket[i] = (key, [1])
            return
    bucket.append((key, value))

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Av

Bkey

Cvalue

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using the old value instead of the new one.

Using the key or index instead of value.

We replace the old value with the new value for the existing key.

4fill in blank

hard

Fill both blanks to complete the get method that returns the value or None if key not found.

DSA Python

def get(self, key):
    index = self._get_bucket_index(key)
    bucket = self.buckets[index]
    for k, v in bucket:
        if k [1] key:
            return [2]
    return None

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A==

B!=

Cv

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' instead of '=='.

Returning the key instead of the value.

We check if the key matches and return the corresponding value.

5fill in blank

hard

Fill both blanks to complete the remove method that deletes a key-value pair if it exists.

DSA Python

def remove(self, key):
    index = self._get_bucket_index(key)
    bucket = self.bucketsindex]
    for i, (k, v) in enumerate(bucket):
        if k [1] key:
            [2] bucket[i
            return True
    return False

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A==

Bdel

C[

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' instead of '=='.

Using remove() method instead of del with index.

Forgetting to use brackets for indexing.

We check if keys match, then delete the item at index i from the bucket list.