78. Binary Search - Efficient Search

You're building a search feature that needs to find an element in a sorted array efficiently. Binary search is the optimal algorithm for sorted arrays.

Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, return its index. Otherwise, return -1.

Requirements

1. Basic Functionality

• Search for target in sorted array
• Return index if found, -1 if not found
• Array is sorted in ascending order
• O(log n) time complexity

Example Usage

binarySearch([-1,0,3,5,9,12], 9); // 4
binarySearch([-1,0,3,5,9,12], 2); // -1

Real-World Context

This problem models real search scenarios:

• Search functionality: Find items in sorted lists
• Database queries: Efficient lookup in sorted data
• Autocomplete: Search in sorted suggestions
• Performance: O(log n) vs O(n) linear search