DigitalOcean Coding Interview Questions
25 DigitalOcean coding interview problems with full optimal solutions — 15 easy, 7 medium, 3 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an DigitalOcean interviewer values, and a FAQ section.
Showing 15 problems of 25
- #1easyfoundational
1. Two Sum
Find two array indices whose values sum to a target — a baseline screen at DigitalOcean for hash-map fluency that feeds into droplet-billing-line reconciliation problems.
- #2easyfoundational
2. Valid Parentheses
Validate balanced brackets in a string — DigitalOcean uses this to check stack fluency that maps to config-file parsing in Terraform-driven droplet provisioning.
- #3easyfoundational
3. Merge Two Sorted Lists
Merge two ascending linked lists into one sorted list — DigitalOcean uses this to test pointer hygiene that resembles merging billing entries from two ledger streams.
- #4easyfoundational
4. Remove Duplicates from Sorted Array
Compact a sorted array so each element appears once and return the new length — DigitalOcean tests this to evaluate in-place transforms that mirror dedupe steps in region-level billing aggregation.
- #5easyfoundational
5. Remove Element
Remove all instances of a target value in-place — DigitalOcean uses this to assess filtering primitives that resemble pruning evicted droplet metrics from a sliding-window batch.
- #6easyfoundational
6. Search Insert Position
Find the index of a target in a sorted array or the insertion point — DigitalOcean uses this to confirm binary-search fluency that supports region-level CIDR-block lookups.
- #7easyfoundational
7. Plus One
Increment a non-negative integer represented as a digit array — DigitalOcean uses this to test boundary handling that resembles incrementing version counters on droplet snapshot IDs.
- #8easyfoundational
8. Merge Sorted Array
Merge two sorted arrays in-place into the first one — DigitalOcean uses this to test two-pointer fluency that maps to merging per-region usage windows into one billing batch.
- #9easyfoundational
9. Binary Tree Inorder Traversal
Return the inorder traversal of a binary tree — DigitalOcean uses this to test tree-walk fluency that mirrors traversing a region/zone/rack hierarchy for billing rollups.
- #10easyfoundational
10. Same Tree
Determine if two binary trees are structurally and value-wise identical — DigitalOcean uses this to test recursive equality logic that maps to comparing droplet config snapshots across regions.
- #11easyfoundational
11. Symmetric Tree
Determine if a binary tree is a mirror of itself around its center — DigitalOcean uses this to assess paired-recursion fluency that surfaces in cross-region failover-pair validation.
- #12easyfoundational
12. Maximum Depth of Binary Tree
Find the maximum depth of a binary tree using DFS — a classic recursion warm-up that DigitalOcean uses to assess comfort with tree traversal.
- #13easyfoundational
13. Balanced Binary Tree
Determine if a binary tree is height-balanced — tests recursive DFS and recognizing when to short-circuit on imbalance.
- #14easyfoundational
14. Path Sum
Check if a root-to-leaf path sums to a target — a foundational DFS pattern DigitalOcean uses to evaluate recursive thinking and edge case awareness.
- #15easyfoundational
15. Pascal's Triangle
Generate the first numRows of Pascal's triangle — tests iterative DP thinking and clean 2D array construction.