Next Permutation of Array in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find the next permutation by swapping the rightmost pair where the left is smaller.

DSA Python

for i in range(len(nums) - 2, -1, -1):
    if nums[i] [1] nums[i + 1]:
        break

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

A==

B!=

C<

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '<' causes wrong pivot detection.

We look for the first index from the right where the number is less than its next number to find the pivot.

2fill in blank

medium

Complete the code to find the element to swap with the pivot for the next permutation.

DSA Python

for j in range(len(nums) - 1, i, -1):
    if nums[j] [1] nums[i]:
        break

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

A<

B>

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' causes swapping with a smaller element, which is incorrect.

We find the rightmost element greater than the pivot to swap with.

3fill in blank

hard

Fix the error in reversing the suffix after swapping to get the next permutation.

DSA Python

nums[i + 1:] = nums[i + 1:][1]

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

A[::-1]

B.reverse()

C.sort()

D.append()

Attempts:

3 left

💡 Hint

Common Mistakes

Using .reverse() returns None and causes assignment error.

We reverse the suffix using slicing with step -1 to get the smallest order after the pivot.

4fill in blank

hard

Fill both blanks to complete the next permutation function that handles the case when no pivot is found.

DSA Python

if i == -1:
    nums[1] = nums[2]

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

A.reverse()

B[:]

C[::-1]

D.sort()

Attempts:

3 left

💡 Hint

Common Mistakes

Using nums = nums[::-1] creates a new list and does not modify in place.

If no pivot is found, the array is in descending order, so we reverse it to get the smallest permutation.

5fill in blank

hard

Fill all three blanks to complete the next permutation function with pivot swap and suffix reversal.

DSA Python

nums[i], nums[j] = nums[1], nums[2]
nums[i + 1:] = nums[i + 1:][3]

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

A[j]

B[i]

C[::-1]

D.reverse()

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping with wrong indices or using .reverse() incorrectly.

Swap the pivot with the found element, then reverse the suffix to get the next permutation.