Frequency Counter Pattern Using Hash Map in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an empty frequency counter dictionary.

DSA Python

freq = [1]

Drag options to blanks, or click blank then click option'

A{}

B[]

C()

Dset()

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets creates a list, not a dictionary.

Using parentheses creates a tuple, not a dictionary.

We use curly braces {} to create an empty dictionary in Python, which is perfect for frequency counting.

2fill in blank

medium

Complete the code to increment the count of character 'char' in the frequency dictionary.

DSA Python

freq[char] = freq.get(char, 0) [1] 1

Drag options to blanks, or click blank then click option'

A//

B+

C*

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' will decrease the count.

Using '*' or '//' will not correctly increment the count.

We add 1 to the current count to increment the frequency of the character.

3fill in blank

hard

Fix the error in the code to check if two strings have the same frequency of characters.

DSA Python

if freq_s1 == [1]:

Drag options to blanks, or click blank then click option'

Afreq_s2

Bfreq

Cfreq_s1

Dfreq_s3

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing the dictionary to itself always returns True.

Using an undefined variable causes errors.

To compare frequencies, we check if the frequency dictionary of the first string equals that of the second string.

4fill in blank

hard

Fill both blanks to create a frequency dictionary for characters in string 'text'.

DSA Python

freq = [1]
for char in [2]:
    freq[char] = freq.get(char, 0) + 1

Drag options to blanks, or click blank then click option'

A{}

Btext

Cstring

D[]

Attempts:

3 left

💡 Hint

Common Mistakes

Using a list instead of a dictionary for frequency.

Looping over an undefined variable.

We start with an empty dictionary {} and loop through each character in the string text to count frequencies.

5fill in blank

hard

Fill all three blanks to create a frequency dictionary for words longer than 3 characters in the list 'words'.

DSA Python

freq = [1]
for word in [2]:
    if len(word) [3] 3:
        freq[word] = freq.get(word, 0) + 1

Drag options to blanks, or click blank then click option'

A{}

Bwords

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong comparison operator.

Looping over a wrong variable.

Not initializing the dictionary.

We create an empty dictionary, loop through the list words, check if word length is greater than 3, then count frequencies.