Recursion Base Case and Recursive Case in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return 1 when n is 0, the base case of recursion.

DSA Typescript

function factorial(n: number): number {
  if (n === [1]) {
    return 1;
  }
  return n * factorial(n - 1);
}

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

An

B0

C-1

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of 0 as the base case condition.

The base case for factorial is when n is 0, returning 1 stops recursion.

2fill in blank

medium

Complete the code to call factorial recursively with n-1.

DSA Typescript

function factorial(n: number): number {
  if (n === 0) {
    return 1;
  }
  return n * factorial([1]);
}

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An - 1

Bn + 1

C1

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Using n + 1 causes infinite recursion.

The recursive call reduces n by 1 each time to reach the base case.

3fill in blank

hard

Fix the error in the base case condition to stop infinite recursion.

DSA Typescript

function sumToN(n: number): number {
  if (n [1] 0) {
    return 0;
  }
  return n + sumToN(n - 1);
}

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A==

B<=

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using < or > causes wrong base case detection.

The base case should check if n equals 0 to stop recursion.

4fill in blank

hard

Fill both blanks to create a recursive function that counts down to zero.

DSA Typescript

function countdown(n: number): void {
  if (n [1] 0) {
    console.log('Done');
    return;
  }
  console.log(n);
  countdown(n [2] 1);
}

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A===

B>

C-

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using < or > incorrectly in base case or recursive call.

The base case checks if n is exactly 0, and the recursive call subtracts 1.

5fill in blank

hard

Fill all three blanks to create a recursive function that sums numbers from 1 to n.

DSA Typescript

function sumNumbers(n: number): number {
  if (n [1] 1) {
    return 1;
  }
  return n [2] sumNumbers(n [3] 1);
}

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

A===

B+

C-

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using > instead of === in base case.

Using subtraction instead of addition in return.

The base case checks if n equals 1, then returns 1. The recursive call adds n to sumNumbers(n - 1).