Merge Sort Algorithm in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to split the array into two halves.

DSA Javascript

const mid = Math.floor(arr.length [1] 2);

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A+

B*

C/

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication instead of division.

Using addition or subtraction which does not find the middle.

We divide the length of the array by 2 to find the middle index for splitting.

2fill in blank

medium

Complete the code to recursively call mergeSort on the left half.

DSA Javascript

const left = mergeSort(arr.slice(0, [1]));

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Aarr.length - 1

Bmid

C0

Darr.length

Attempts:

3 left

💡 Hint

Common Mistakes

Using the full array length instead of mid.

Using incorrect slice indices causing wrong subarrays.

We slice the array from 0 to mid to get the left half for recursive sorting.

3fill in blank

hard

Fix the error in the merge function to correctly compare elements.

DSA Javascript

if (left[i] [1] right[j]) {

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A<

B>

C===

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using greater than which reverses sorting order.

Using equality or inequality which does not sort properly.

We compare if left[i] is less than right[j] to merge in sorted order.

4fill in blank

hard

Fill both blanks to complete the while loop conditions for merging.

DSA Javascript

while (i [1] left.length && j [2] right.length) {

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A<

B>

C<=

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using greater than or equal which causes index errors.

Using less than or equal which may cause out of bounds.

We continue merging while i and j are less than their array lengths.

5fill in blank

hard

Fill all three blanks to complete the return statement merging arrays.

DSA Javascript

return [...merged, ...left.slice([1]), ...right.slice([2])];

let i = [3];

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Ai

Bj

C0

Dmerged.length

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variables for slicing leftover elements.

Initializing i incorrectly causing merge errors.

We slice left from i and right from j to add remaining elements; i starts at 0.