Find Peak Element Using Binary Search in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the middle index for binary search.

DSA Typescript

let mid = Math.[1]((left + right) / 2);

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

Aceil

Bfloor

Cround

Dtrunc

Attempts:

3 left

💡 Hint

Common Mistakes

Using Math.ceil causes index to go out of range sometimes.

Using Math.round can cause uneven splits.

We use Math.floor to get the middle index as an integer by rounding down.

2fill in blank

medium

Complete the condition to check if mid element is a peak.

DSA Typescript

if ((mid === 0 || nums[mid] > nums[mid - 1]) && (mid === nums.length - 1 || nums[mid] > nums[[1]])) {

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

Anums.length

Bmid - 1

Cmid

Dmid + 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using mid - 1 instead of mid + 1 causes wrong comparison.

Using nums.length as index causes out of bounds error.

We compare the mid element with the next element at mid + 1 to check if it is greater.

3fill in blank

hard

Fix the error in updating the left pointer when mid element is less than the next element.

DSA Typescript

if (nums[mid] < nums[mid + 1]) {
    left = [1];
} else {
    right = mid;
}

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Amid + 1

Bmid

Cleft + 1

Dright - 1

Attempts:

3 left

💡 Hint

Common Mistakes

Setting left to mid causes infinite loop when mid doesn't change.

Using right - 1 is wrong direction.

We move left to mid + 1 to search the right half where a peak may exist.

4fill in blank

hard

Fill both blanks to complete the binary search loop condition and return statement.

DSA Typescript

while ([1] < [2]) {
    // binary search steps
}
return left;

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

Aleft

Bright

Cmid

Dnums.length

Attempts:

3 left

💡 Hint

Common Mistakes

Using mid in loop condition causes errors.

Returning right instead of left can be confusing but works; here we use left.

The loop runs while left < right. After the loop, left is the peak index.

5fill in blank

hard

Fill all three blanks to complete the function signature, initialize pointers, and return the peak index.

DSA Typescript

function findPeakElement([1]: number[]): number {
    let [2] = 0;
    let right = nums.length - 1;
    while (left < right) {
        let mid = Math.floor((left + right) / 2);
        if (nums[mid] < nums[mid + 1]) {
            left = mid + 1;
        } else {
            right = mid;
        }
    }
    return [3];
}

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

Anums

Bleft

Dright

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong parameter name causes errors.

Returning right instead of left is possible but inconsistent here.

The function takes nums array, initializes left pointer, and returns left as the peak index.