Find Minimum in Rotated Sorted Array in DSA Javascript - Practice Problems & Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Find the minimum element output

What is the output of this JavaScript code that finds the minimum in a rotated sorted array?

DSA Javascript

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

console.log(findMin([4,5,6,7,0,1,2]));

A 4

B 7

C 1

D 0

💡 Hint

Think about how the binary search narrows down the smallest element in the rotated array.

The code uses binary search to find the smallest element. Since 0 is the smallest in the rotated array [4,5,6,7,0,1,2], it returns 0.

❓ Predict Output

intermediate

Minimum element in a non-rotated sorted array

What will the function output for a sorted array that is not rotated?

DSA Javascript

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

console.log(findMin([1,2,3,4,5,6,7]));

A 7

B 1

C 4

D 3

💡 Hint

If the array is not rotated, the smallest element is the first element.

Since the array is sorted and not rotated, the smallest element is the first element, which is 1.

🔧 Debug

advanced

Identify the error in this minimum finder

What error will this code produce when trying to find the minimum in a rotated sorted array?

DSA Javascript

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

console.log(findMin([3,1,2]));

A Returns wrong minimum value 3

B IndexError

C TypeError

D Returns correct minimum value 1

💡 Hint

Check the loop condition and how right pointer is updated.

The loop condition and right pointer update cause the function to miss the correct minimum and return 3 instead of 1.

❓ Predict Output

advanced

Output of minimum finder with duplicates

What is the output of this code when the rotated sorted array contains duplicates?

DSA Javascript

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

console.log(findMin([2,2,2,0,1,2]));

A 0

B 1

C 2

D Error

💡 Hint

Duplicates require careful handling to avoid missing the minimum.

The code handles duplicates by decreasing right pointer when equal, eventually finding the minimum 0.

🧠 Conceptual

expert

Why binary search works for rotated sorted arrays

Why does binary search still work to find the minimum element in a rotated sorted array?

A Because linear search is too slow and binary search guesses the minimum randomly

B Because the array is fully sorted and binary search always works on sorted arrays

C Because the array is partially sorted and we can compare middle and right elements to decide search direction

D Because the minimum element is always at the middle index after rotation

💡 Hint

Think about how the rotated array keeps some sorted order properties.

Binary search works because the rotated array is partially sorted, allowing comparison between middle and right elements to decide which half contains the minimum.