Two Pointers Questions at Expedia: What to Expect

Two Pointers is a high-frequency pattern at Expedia, appearing in roughly 13% of their technical interview questions. For a company that builds complex travel search and booking systems, this makes sense. The pattern is fundamental for efficiently processing sorted arrays, strings, or linked lists—core data structures used in filtering flight results, managing date ranges, or optimizing itinerary calculations. Mastering it demonstrates you can move beyond brute-force solutions to write optimized, scalable code, a critical skill for Expedia's high-traffic platforms.

What to Expect — Types of Problems

Expedia's Two Pointers questions typically fall into three categories, often framed in a travel context.

1. Opposite-End Pointers: Used on pre-sorted arrays. Problems involve finding pairs that meet a condition, like "find two travel packages whose total cost equals a budget" or "find all unique destination pairs within a maximum travel distance." The pointers start at the beginning and end, moving inward based on comparisons.
2. Fast & Slow Pointers: Primarily for linked lists or sequences. You'll encounter cycle detection ("does this linked list of booking connections have a cycle?") or finding a middle element, testing your understanding of pointer manipulation and data structure traversal.
3. Sliding Window: A variant for subarrays or substrings. Expect problems about contiguous sequences, such as "find the longest substring with at most K different flight codes" or "the maximum average hotel rating over a fixed trip length." This tests your ability to manage a dynamic window of data efficiently.

The problems are often medium difficulty, requiring you to not only implement the pattern but also handle edge cases and explain your optimization.

How to Prepare — Study Tips with One Code Example

Start by deeply understanding the classic Two Sum II problem (sorted array). It's the foundation. Then, practice each category above. Always ask: is the data sorted? If yes, opposite-end pointers are likely. For subarray/substring problems, consider a sliding window. For linked lists, think fast/slow.

When practicing, write the code by hand first, then run it. Verbally walk through your logic. Here is the core opposite-end pointers pattern for finding a target sum in a sorted array:

def two_sum_sorted(numbers, target):
    left, right = 0, len(numbers) - 1
    while left < right:
        current_sum = numbers[left] + numbers[right]
        if current_sum == target:
            return [left + 1, right + 1]  # 1-indexed
        elif current_sum < target:
            left += 1  # Need a larger sum
        else:
            right -= 1  # Need a smaller sum
    return []

Recommended Practice Order

Build competence sequentially. First, master the basic opposite-direction pattern (Two Sum II, Valid Palindrome). Second, tackle sliding window problems (Longest Substring Without Repeating Characters, Minimum Size Subarray Sum). Third, practice fast and slow pointers (Linked List Cycle, Middle of the Linked List). Finally, solve Expedia-specific questions to acclimate to their problem framing and difficulty level.

Practice Two Pointers at Expedia