Find Peak Element Using Binary Search in DSA Javascript - Build from Scratch

Find Peak Element Using Binary Search

📖 Scenario: Imagine you have a list of numbers representing heights of hills along a trail. You want to find a hill that is taller than its neighbors, called a peak.

🎯 Goal: Build a program that finds a peak element in a list of numbers using binary search. A peak element is one that is greater than its neighbors.

📋 What You'll Learn

Create an array called heights with exact values

Create two variables left and right to hold the start and end indexes

Use a while loop with binary search logic to find a peak element index

Print the index of the peak element found

💡 Why This Matters

🌍 Real World

Finding peak elements is useful in signal processing, stock market analysis, and identifying local maxima in data.

💼 Career

Binary search is a fundamental algorithm technique used in software engineering for efficient searching and optimization problems.

1

Create the heights array

Create an array called heights with these exact values: [1, 3, 20, 4, 1, 0]

DSA Javascript

// Your code here

Hint

Use const heights = [1, 3, 20, 4, 1, 0]; to create the array.

2

Set up binary search boundaries

Create two variables called left and right. Set left to 0 and right to heights.length - 1.

DSA Javascript

const heights = [1, 3, 20, 4, 1, 0];
// Your code here

Hint

Use let left = 0; and let right = heights.length - 1;.

3

Implement binary search to find peak

Use a while loop with condition left < right. Inside the loop, create a variable mid as the middle index. If heights[mid] is less than heights[mid + 1], set left to mid + 1. Otherwise, set right to mid.

DSA Javascript

const heights = [1, 3, 20, 4, 1, 0];
let left = 0;
let right = heights.length - 1;
// Your code here

Hint

Use binary search logic comparing heights[mid] and heights[mid + 1] to move left or right.

4

Print the peak element index

Print the value of left, which is the index of the peak element found.

DSA Javascript

const heights = [1, 3, 20, 4, 1, 0];
let left = 0;
let right = heights.length - 1;

while (left < right) {
    let mid = Math.floor((left + right) / 2);
    if (heights[mid] < heights[mid + 1]) {
        left = mid + 1;
    } else {
        right = mid;
    }
}
// Your code here

Hint

Use console.log(left); to print the peak index.