Prefix Sum Array in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the prefix sum array's first element.

DSA C

prefix_sum[0] = [1];

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A-1

Barr[0]

Carr[1]

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Setting prefix_sum[0] to 0 instead of arr[0]

Using arr[1] which is the second element

Initializing with -1 which is incorrect

The first element of the prefix sum array should be the first element of the original array.

2fill in blank

medium

Complete the code to compute the prefix sum at index i inside the loop.

DSA C

prefix_sum[i] = prefix_sum[i - 1] [1] arr[i];

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A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction instead of addition

Using multiplication or division which are incorrect here

Each prefix sum element is the sum of the previous prefix sum and the current array element.

3fill in blank

hard

Fix the error in the loop condition to correctly iterate over the array elements.

DSA C

for (int i = 1; i [1] n; i++) {

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A>

B<=

C>=

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>=' or '>' which causes no iterations or wrong iterations

Using '<=' which causes out-of-bounds access

The loop should run while i is less than n to avoid going out of array bounds.

4fill in blank

hard

Fill both blanks to compute the prefix sum array using a for loop.

DSA C

for (int [1] = 1; [2] < n; [1]++) {
    prefix_sum[[1]] = prefix_sum[[1] - 1] + arr[[1]];
}

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

Ai

Bj

Ck

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in loop parts causing errors

Using uncommon variable names that confuse the logic

The loop variable should be consistent; 'i' is commonly used for indexing.

5fill in blank

hard

Fill all three blanks to create a prefix sum array and print its elements.

DSA C

int prefix_sum[n];
prefix_sum[0] = arr[0];
for (int [1] = 1; [2] < n; [1]++) {
    prefix_sum[[1]] = prefix_sum[[1] - 1] + arr[[1]];
}
for (int [3] = 0; [3] < n; [3]++) {
    printf("%d ", prefix_sum[[3]]);
}

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

Ai

Bj

Ck

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same variable for both loops causing logic errors

Using inconsistent variable names inside loops

Use 'i' for the prefix sum loop and 'j' for the print loop to avoid confusion.