Traversal Forward and Backward in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print all elements of the list forward.

DSA Python

for i in range(len(lst)):
    print(lst[[1]])

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

Alen(lst)

Bi

C0

Dlst[i]

Attempts:

3 left

💡 Hint

Common Mistakes

Using the list itself as an index like lst[lst[i]]

Using a fixed index like 0 instead of the loop variable

We use the loop variable 'i' to access each element in the list by index.

2fill in blank

medium

Complete the code to print all elements of the list backward.

DSA Python

for i in range(len(lst)-1, [1], -1):
    print(lst[i])

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

A1

Blen(lst)

C-1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 as stop index which excludes index 0

Using len(lst) which is out of range

To go backward through the list, we start from the last index and go down to -1 (exclusive) to include index 0.

3fill in blank

hard

Fix the error in the code to traverse the list forward and print elements.

DSA Python

i = 0
while i < [1]:
    print(lst[i])
    i += 1

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

Alen(lst)

Blst

Ci

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing 'i' with the list itself instead of its length

Using a fixed number instead of the list length

The loop should run while 'i' is less than the length of the list to cover all elements.

4fill in blank

hard

Fill both blanks to create a dictionary of word lengths for words longer than 3 characters.

DSA Python

{word: [1] for word in words if len(word) [2] 3}

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

Alen(word)

B<

C>

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word itself as the value instead of its length

Using '<' instead of '>' in the condition

We want the length of each word as the value and only include words longer than 3 characters.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase keys and values for positive values only.

DSA Python

result = {{ [1]: [2] for k, v in data.items() if v [3] 0 }}

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

Ak.upper()

Bv

C>

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Using original keys instead of uppercase

Using '<' instead of '>' in the condition

Using keys as values

Keys are uppercase versions of k, values are v, and we include only positive values (v > 0).