Array Questions at Salesforce: What to Expect

Array questions make up 55% of Salesforce's technical interview problem set (104 out of 189). This isn't an accident. Salesforce's core platform—managing CRM data, objects, records, and bulk operations—fundamentally relies on efficient data manipulation. Arrays represent ordered lists of records, in-memory data processing, and sequences of API events. Your ability to traverse, transform, and optimize array operations directly mirrors the real-world work of building scalable features on the Salesforce platform. Mastering these questions is non-negotiable for passing the technical screen.

What to Expect — Types of Problems

Salesforce array problems test core algorithmic thinking applied to data sequences. Expect heavy emphasis on:

• Two Pointers & Sliding Window: For finding pairs, subarrays, or removing duplicates in-place. Common for processing sorted data streams or contiguous record sequences.
• Prefix Sum & Cumulative Calculations: Essential for range queries, running totals, and dashboard metric calculations—common in analytics features.
• In-place Array Modification: Simulating operations on records without extra space, reflecting memory constraints in large data processing.
• Cyclic Sort & Index Manipulation: Problems involving missing/duplicate numbers or rearranging elements, analogous to data integrity checks.
• Basic Sorting & Searching: Often the first step in more complex problems, testing foundational knowledge.

You will rarely see highly abstract or purely mathematical array puzzles. Problems are grounded in data processing logic.

How to Prepare — Study Tips with One Code Example

Focus on pattern recognition, not memorization. For each problem type, internalize the algorithmic approach and practice deriving the solution. Always articulate your thought process before coding. Optimize for time and space complexity explicitly.

A key pattern is the Two-Pointer Swap for In-place Modification, frequently used to move specific elements (like zeros) to the end while maintaining the relative order of others. Here is the standard approach:

def moveZeroes(nums):
    """
    Moves all zeros to the end in-place.
    """
    insert_pos = 0  # Pointer for the next non-zero element's position

    for i in range(len(nums)):
        if nums[i] != 0:
            nums[insert_pos], nums[i] = nums[i], nums[insert_pos]
            insert_pos += 1
    # No return, modifies nums in-place

The pattern uses a "boundary" pointer (insertPos) to track where the next valid (non-zero) element should go. Every non-zero element is swapped to this position. This runs in O(n) time and O(1) space.

Recommended Practice Order

1. Foundation: Basic traversal, sorting, and binary search.
2. Core Patterns: Two-pointers (for pairs and subarrays) and sliding window.
3. In-place Operations: Element movement, deduplication, and cyclic sort.
4. Efficiency Techniques: Prefix sum and cumulative array strategies.
5. Salesforce-specific List: Tackle the company-tagged problems last, applying your pattern knowledge under timed conditions.

Practice Array at Salesforce