Shell Sort Algorithm in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the gap for Shell Sort.

DSA Javascript

let n = arr.length;
let gap = [1];

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

A1

Bn

CMath.floor(n / 2)

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Setting gap to 0 causes no sorting steps.

Setting gap to n means no initial gap reduction.

The gap starts as half the array length, which helps compare distant elements first.

2fill in blank

medium

Complete the code to reduce the gap after each pass in Shell Sort.

DSA Javascript

while (gap > 0) {
  // sorting logic here
  gap = [1];
}

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

AMath.floor(gap / 2)

Bgap - 1

Cgap * 2

Dgap + 1

Attempts:

3 left

💡 Hint

Common Mistakes

Increasing the gap causes infinite loops.

Subtracting 1 may not reduce gap properly for large arrays.

The gap is reduced by half each time to gradually compare closer elements.

3fill in blank

hard

Fix the error in the inner loop condition to correctly perform insertion sort with the gap.

DSA Javascript

for (let i = gap; i < n; i++) {
  let temp = arr[i];
  let j = i;
  while (j >= gap && arr[j - [1]] > temp) {
    arr[j] = arr[j - gap];
    j -= gap;
  }
  arr[j] = temp;
}

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

Agap

B1

Ci

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 causes incorrect comparisons and sorting.

Using i or n causes index errors.

The inner loop compares elements that are 'gap' positions apart, so subtract gap.

4fill in blank

hard

Fill both blanks to complete the gap-based insertion sort step inside the while loop.

DSA Javascript

while (j >= [1] && arr[j - [2]] > temp) {
  arr[j] = arr[j - gap];
  j -= gap;
}

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

Agap

B1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of gap causes wrong element comparisons.

Using 0 causes index errors.

Both blanks use 'gap' because the sorting compares and shifts elements gap positions apart.

5fill in blank

hard

Fill all three blanks to complete the Shell Sort function.

DSA Javascript

function shellSort(arr) {
  let n = arr.length;
  let gap = [1];
  while (gap > 0) {
    for (let i = gap; i < n; i++) {
      let temp = arr[i];
      let j = i;
      while (j >= [2] && arr[j - [3]] > temp) {
        arr[j] = arr[j - gap];
        j -= gap;
      }
      arr[j] = temp;
    }
    gap = Math.floor(gap / 2);
  }
  return arr;
}

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

AMath.floor(n / 2)

Bgap

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of gap in the while loop causes incorrect sorting.

Not initializing gap properly causes no sorting.

The gap starts at half the array length, and the inner loop uses gap to compare and shift elements.