Binary Search as Divide and Conquer in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find the middle index in binary search.

DSA Typescript

const mid = Math.floor((low + [1]) / 2);

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

Ahigh

Bmid

Clow

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using mid instead of high causes incorrect calculation.

Using low twice results in always the same index.

The middle index is calculated by averaging low and high indices.

2fill in blank

medium

Complete the code to check if the middle element is the target.

DSA Typescript

if (arr[mid] === [1]) { return mid; }

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Aarr

Bmid

Ctarget

Dlow

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing arr[mid] with mid instead of target.

Using low or arr instead of target.

We compare the middle element with the target value to find a match.

3fill in blank

hard

Fix the error in updating the low index when target is greater than middle element.

DSA Typescript

if (arr[mid] < target) { low = [1]; }

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Alow + 1

Bmid + 1

Cmid - 1

Dhigh - 1

Attempts:

3 left

💡 Hint

Common Mistakes

Setting low to mid - 1 causes infinite loop or wrong search.

Using high or low + 1 incorrectly.

When target is greater, we move low to mid + 1 to search the right half.

4fill in blank

hard

Fill both blanks to update high index when target is less than middle element and to return -1 if not found.

DSA Typescript

if (arr[mid] > target) { [1] = mid - 1; } else if (low > high) { return [2]; }

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Ahigh

B-1

Clow

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Updating low instead of high.

Returning 0 instead of -1 when not found.

When target is less, high moves to mid - 1. If low passes high, target is not found, so return -1.

5fill in blank

hard

Fill all three blanks to complete the recursive binary search function.

DSA Typescript

function binarySearch(arr: number[], target: number, low: number, high: number): number {
  if (low > high) return [1];
  const mid = Math.floor((low + [2]) / 2);
  if (arr[mid] === target) return mid;
  else if (arr[mid] < target) return binarySearch(arr, target, mid + 1, [3]);
  else return binarySearch(arr, target, low, mid - 1);
}

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

A-1

Bhigh

Clow

Dmid

Attempts:

3 left

💡 Hint

Common Mistakes

Returning 0 instead of -1 in base case.

Using low instead of high in mid calculation.

Passing wrong high value in recursive call.

Return -1 if not found. Calculate mid using low and high. Search right half by updating low to mid + 1 and keeping high.