Count and Say Problem in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the first term of the count-and-say sequence.

DSA Python

def count_and_say(n):
    result = [1]
    return result

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A"1"

B1

C"0"

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using integer 1 instead of string "1".

Starting with "0" or 0 which is incorrect.

The count-and-say sequence starts with the string "1" as the first term.

2fill in blank

medium

Complete the code to iterate from 1 to n-1 to build the sequence.

DSA Python

for i in range([1], n):
    pass

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An

B0

C1

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Starting loop from 0 which repeats the first term.

Starting from n which skips all iterations.

The loop starts from 1 because the first term is already initialized.

3fill in blank

hard

Fix the error in the inner loop that counts consecutive characters.

DSA Python

count = 1
for j in range(1, len(result)):
    if result[j] == result[j-1]:
        count [1] 1
    else:
        count = 1

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A*=

B-=

C=

D+=

Attempts:

3 left

💡 Hint

Common Mistakes

Using = which resets count instead of increasing.

Using -= which decreases count incorrectly.

We increase count by 1 when consecutive characters match, so use +=.

4fill in blank

hard

Fill both blanks to append count and character to the next sequence string.

DSA Python

next_seq += str([1]) + [2]

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Acount

Bresult[j-1]

Cresult[j]

D"count"

Attempts:

3 left

💡 Hint

Common Mistakes

Appending the current character instead of previous.

Appending count without converting to string.

Append the count as string and the previous character counted.

5fill in blank

hard

Fill all three blanks to complete the count-and-say function logic.

DSA Python

def count_and_say(n):
    result = [1]
    for i in range([2], n):
        next_seq = ""
        count = 1
        for j in range(1, len(result)):
            if result[j] == result[j-1]:
                count [3] 1
            else:
                next_seq += str(count) + result[j-1]
                count = 1
        next_seq += str(count) + result[-1]
        result = next_seq
    return result

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

A"1"

B1

C+=

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using integer 1 instead of string "1" for result.

Starting loop from 0 instead of 1.

Using = instead of += to increment count.

The function starts with "1" as string, loops from 1 to n, and increments count with +=.