Activity Selection Problem in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to sort activities by their finish time.

DSA Typescript

activities.sort((a, b) => a.[1] - b.finish);

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Aduration

Bfinish

Cstart

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Sorting by start time instead of finish time.

Using a wrong property name.

Sorting activities by their finish time helps us select the maximum number of non-overlapping activities.

2fill in blank

medium

Complete the code to select the first activity after sorting.

DSA Typescript

selected.push(activities[[1]]);

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Aactivities.length - 1

B1

Cactivities.length

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Starting selection from index 1 instead of 0.

Using the last index instead of the first.

The first activity after sorting by finish time is at index 0 and is always selected first.

3fill in blank

hard

Fix the error in the condition to check if the next activity can be selected.

DSA Typescript

if (activities[i].start >= [1]) {

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

Aactivities[i-1].finish

Bselected[selected.length]

Cselected[selected.length - 1].finish

Dactivities[0].start

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing with the wrong activity's finish time.

Using an out-of-range index.

We compare the start time of the current activity with the finish time of the last selected activity.

4fill in blank

hard

Fill both blanks to complete the loop that selects compatible activities.

DSA Typescript

for (let i = [1]; i < activities.length; i++) {
  if (activities[i].start >= [2]) {
    selected.push(activities[i]);
  }
}

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

A1

B0

Cselected[selected.length - 1].finish

Dactivities[0].start

Attempts:

3 left

💡 Hint

Common Mistakes

Starting loop from 0 causing duplicate selection.

Comparing with wrong finish time.

Start loop from 1 because first activity is already selected. Compare start time with last selected activity's finish time.

5fill in blank

hard

Fill all three blanks to create a function that returns the maximum set of compatible activities.

DSA Typescript

function selectActivities(activities: {start: number, finish: number}[]): {start: number, finish: number}[] {
  activities.sort((a, b) => a.[1] - b.[2]);
  const selected = [activities[0]];
  for (let i = [3]; i < activities.length; i++) {
    if (activities[i].start >= selected[selected.length - 1].finish) {
      selected.push(activities[i]);
    }
  }
  return selected;
}

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

Afinish

Bstart

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Sorting by start time instead of finish time.

Starting loop from 0 causing duplicate selection.

Sort by finish time (both a and b). Start loop from 1 since first activity is pre-selected.