Binary Search: The Complete Interview Guide

Binary search is a fundamental algorithm that every software engineer must master. It appears in approximately 20% of all FAANG coding interviews.

Understanding Binary Search

Binary search is an efficient algorithm for finding a target value within a sorted array. It works by repeatedly dividing the search interval in half.

Classic Binary Search Template

def binary_search(arr, target):
    left, right = 0, len(arr) - 1

    while left <= right:
        mid = left + (right - left) // 2

        if arr[mid] == target:
            return mid
        elif arr[mid] < target:
            left = mid + 1
        else:
            right = mid - 1

    return -1

Common Variations

1. Search in Rotated Sorted Array
2. Find Peak Element
3. Binary Search on Answer
4. Search in 2D Matrix

Key Insights

• Always avoid integer overflow when calculating mid
• Consider edge cases: empty array, single element
• Think about whether you need left <= right or left < right

Practice Problems

Start with these essential problems:

• Search Insert Position
• Find First and Last Position
• Find Minimum in Rotated Sorted Array

Master binary search and unlock a huge category of interview problems!