Search in Rotated Sorted Array in DSA Javascript - Build from Scratch

Search in Rotated Sorted Array

📖 Scenario: Imagine you have a list of numbers that was originally sorted from smallest to largest. But then, someone took a part of the list from the front and moved it to the end. This is called a rotated sorted array.For example, the list [1, 2, 3, 4, 5] might become [3, 4, 5, 1, 2] after rotation.

🎯 Goal: You will write a program to find the position of a number in this rotated list. If the number is not in the list, your program should say it is not found.

📋 What You'll Learn

Create an array called rotatedArray with exact numbers given.

Create a variable called target to hold the number to find.

Write a function called searchRotatedArray that finds the index of target in rotatedArray using a smart search.

Print the index found or -1 if the number is not in the array.

💡 Why This Matters

🌍 Real World

Rotated sorted arrays appear in systems where data is shifted or rotated for performance or storage reasons, like in circular buffers or time-based logs.

💼 Career

Understanding how to search efficiently in rotated sorted arrays is useful for software engineers working on search algorithms, database indexing, and system optimizations.

1

Create the rotated sorted array

Create an array called rotatedArray with these exact numbers in order: 15, 18, 2, 3, 6, 12

DSA Javascript

// Your code here

Hint

Use square brackets [] to create the array and separate numbers with commas.

2

Set the target number to find

Create a variable called target and set it to the number 3

DSA Javascript

const rotatedArray = [15, 18, 2, 3, 6, 12];
// Your code here

Hint

Use const to create the variable and assign the number 3.

3

Write the search function for rotated sorted array

Write a function called searchRotatedArray that takes arr and target as inputs and returns the index of target in arr. Use a while loop with variables left and right to do a smart search in the rotated array.

DSA Javascript

const rotatedArray = [15, 18, 2, 3, 6, 12];
const target = 3;

// Write searchRotatedArray function here
// Your code here

Hint

Use binary search logic but adjust the left and right pointers based on which side is sorted.

4

Print the index of the target

Use console.log to print the result of calling searchRotatedArray with rotatedArray and target.

DSA Javascript

const rotatedArray = [15, 18, 2, 3, 6, 12];
const target = 3;

function searchRotatedArray(arr, target) {
    let left = 0;
    let right = arr.length - 1;
    while (left = arr[left] && target  arr[mid] && target <= arr[right]) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }
    }
    return -1;
}

// Print the index of target
// Your code here

Hint

Call the function with rotatedArray and target and print the result.