Generate All Subsets Powerset in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the result array for storing subsets.

DSA Typescript

function subsets(nums: number[]): number[][] {
  const result = [1];
  return result;
}

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

A{}

B[]

Cnull

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using {} which creates an object instead of an array.

Using null or 0 which are not arrays.

We initialize result as an empty array to store all subsets.

2fill in blank

medium

Complete the code to start the recursive backtracking call.

DSA Typescript

function subsets(nums: number[]): number[][] {
  const result: number[][] = [];
  function backtrack(start: number, path: number[]) {
    result.push([...path]);
    for (let i = start; i < nums.length; i++) {
      path.push(nums[i]);
      backtrack([1], path);
      path.pop();
    }
  }
  backtrack(0, []);
  return result;
}

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

Ai + 1

Bstart + 1

Ci

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Passing start + 1 which skips elements incorrectly.

Passing i which causes infinite recursion.

We call backtrack with i + 1 to move to the next element after including nums[i].

3fill in blank

hard

Fix the error in the base case to correctly add the current subset to the result.

DSA Typescript

function subsets(nums: number[]): number[][] {
  const result: number[][] = [];
  function backtrack(start: number, path: number[]) {
    [1];
    for (let i = start; i < nums.length; i++) {
      path.push(nums[i]);
      backtrack(i + 1, path);
      path.pop();
    }
  }
  backtrack(0, []);
  return result;
}

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

Aresult.push(path.slice())

Bresult.push(path)

Cresult.push([...path])

Dresult.push(path.pop())

Attempts:

3 left

💡 Hint

Common Mistakes

Pushing path directly causes all entries to reference the same array.

Using path.pop() removes elements and returns a number, not the subset.

We push a copy of path using spread syntax to avoid mutation issues.

4fill in blank

hard

Fill both blanks to complete the for loop that generates subsets.

DSA Typescript

function subsets(nums: number[]): number[][] {
  const result: number[][] = [];
  function backtrack([1]: number, path: number[]) {
    result.push([...path]);
    for (let i = [2]; i < nums.length; i++) {
      path.push(nums[i]);
      backtrack(i + 1, path);
      path.pop();
    }
  }
  backtrack(0, []);
  return result;
}

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

Astart

Bindex

C0

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names causing confusion.

Starting loop at 0 inside backtrack causes duplicates.

The parameter and loop variable both use 'start' to track the current index.

5fill in blank

hard

Fill all three blanks to complete the subsets function with backtracking.

DSA Typescript

function subsets(nums: number[]): number[][] {
  const result: number[][] = [];
  function backtrack([1]: number, [2]: number[]) {
    result.push([...[3]]);
    for (let i = start; i < nums.length; i++) {
      path.push(nums[i]);
      backtrack(i + 1, path);
      path.pop();
    }
  }
  backtrack(0, []);
  return result;
}

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

Astart

Bpath

Dnums

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names causing reference errors.

Pushing the wrong variable to result.

The function parameters are 'start' and 'path', and we push a copy of 'path'.