Kadane's Algorithm Maximum Subarray in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the variable that keeps track of the current subarray sum.

DSA Python

def max_subarray_sum(nums):
    current_sum = [1]
    max_sum = nums[0]
    for num in nums[1:]:
        current_sum = max(num, current_sum + num)
        max_sum = max(max_sum, current_sum)
    return max_sum

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

A0

B1

Cfloat('-inf')

Dnums[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing current_sum to 0 causes incorrect results when all numbers are negative.

We start the current sum with the first element to correctly handle arrays with all negative numbers.

2fill in blank

medium

Complete the code to update the current sum by choosing the maximum between the current number and the sum including it.

DSA Python

def max_subarray_sum(nums):
    current_sum = nums[0]
    max_sum = nums[0]
    for num in nums[1:]:
        current_sum = [1]
        max_sum = max(max_sum, current_sum)
    return max_sum

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

Amax(num, current_sum + num)

Bnum + current_sum

Cmin(num, current_sum + num)

Dcurrent_sum - num

Attempts:

3 left

💡 Hint

Common Mistakes

Using min instead of max causes wrong subarray sums.

Not including the current number in the sum.

We choose the maximum between starting fresh at the current number or continuing the previous subarray.

3fill in blank

hard

Fix the error in the loop to correctly iterate over the array starting from the second element.

DSA Python

def max_subarray_sum(nums):
    current_sum = nums[0]
    max_sum = nums[0]
    for num in nums[1]:
        current_sum = max(num, current_sum + num)
        max_sum = max(max_sum, current_sum)
    return max_sum

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A[0:]

B[:1]

C[1:]

D[2:]

Attempts:

3 left

💡 Hint

Common Mistakes

Using [:1] iterates only the first element.

Using [0:] includes the first element again causing double counting.

We start iterating from the second element because the first is already used to initialize sums.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps each number to its square if the number is positive.

DSA Python

squares = {num: num[1]2 for num in nums if num [2] 0}

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A**

B>

C<

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' instead of '**' for squares.

Using '<' instead of '>' for filtering positive numbers.

We use '**' for exponentiation and '>' to check if the number is positive.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps uppercase words to their lengths if length is greater than 3.

DSA Python

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

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Aword.upper()

Blen(word)

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

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

Mapping word instead of word.upper().

We convert words to uppercase, map to their lengths, and filter words longer than 3 characters.