Subarray Sum Equals K Using Hash Map in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the variable that stores the count of subarrays.

DSA C

int count = [1];

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

A1

B0

C-1

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing count to 1 or negative values.

We start counting subarrays from zero, so initializing count to 0 is correct.

2fill in blank

medium

Complete the code to update the cumulative sum with the current array element.

DSA C

sum [1]= nums[i];

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

A-

B/

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication instead of addition.

We add the current element to the cumulative sum to keep track of the total so far.

3fill in blank

hard

Fix the error in the condition that checks if (sum - k) exists in the hash map.

DSA C

if (hashMapContains(hashMap, sum [1] k)) {

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

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or multiplication instead of subtraction.

We check if sum - k exists because it indicates a subarray summing to k.

4fill in blank

hard

Fill both blanks to update the count and the hash map correctly.

DSA C

count += hashMapGet(hashMap, sum [1] k);
hashMapPut(hashMap, sum, hashMapGet(hashMap, sum) [2] 1);

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

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of subtraction in first blank or wrong operator in second blank.

We add the frequency of (sum - k) to count and increment the frequency of sum by 1.

5fill in blank

hard

Fill all three blanks to initialize the hash map, insert the base case, and iterate over the array.

DSA C

HashMap *hashMap = [1]();
hashMapPut(hashMap, 0, [2]);
for (int i = 0; i [3] n; i++) {

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

AhashMapCreate

B1

C<

DhashMapInit

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong function name, wrong base frequency (like 0), or wrong loop condition.

We create the hash map, set the base case frequency of sum 0 to 1, and loop while i is less than n.