Problem database last updated: June 20, 2025
3 problems · 1 Easy, 2 Medium, 0 Hard · Ranked #321 of 458
1 Easy
33% · avg 23%
2 Medium
67% · avg 59%
0 Hard
0% · avg 18%
Based on 3 reported problems, DeltaX interviews are easier than average - only 0% Hard compared to 18% across all companies. The majority (67%) of questions are Medium difficulty, which is typical for companies that want to see solid fundamentals without excessive trick questions.
Compared to the industry average, DeltaX puts unusual emphasis on math (66.7% of problems, 5.3x the industry average), hash-table (66.7% of problems, 3x the industry average), string (66.7% of problems, 2.4x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are hash-table (66.7%), math (66.7%), string (66.7%), array (33.3%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Roman to Integer Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. | Easy | Very Likely | hash-tablemathstring | Solve |
Longest Consecutive Sequence Given an unsorted array of integers nums, return the length of the longest consecutive elements sequence. | Medium | Likely | arrayhash-tableunion-find | Solve |
Different Ways to Add Parentheses Given a string expression of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. Y... | Medium | Likely | mathstringdynamic-programming | Solve |
Roman to Integer
SolveRoman numerals are represented by seven different symbols: I, V, X, L, C, D and M.
Longest Consecutive Sequence
SolveGiven an unsorted array of integers nums, return the length of the longest consecutive elements sequence.
Different Ways to Add Parentheses
SolveGiven a string expression of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. Y...
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent DeltaX interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
DeltaX interviews focus heavily on hash-table, math, string problems. If you're short on time, these are the categories to prioritize. The problems on this page are sorted by frequency, so start from the top and work your way down.
Beyond solving problems, practice explaining your approach. DeltaX interviewers care about your thought process - how you break down a problem, consider edge cases, and evaluate tradeoffs between solutions. A clean O(n) solution you can explain clearly beats an O(log n) solution you can't articulate.
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DeltaX has been reported to ask 3 distinct coding problems. The most common topics are hash-table, math, string. 1 are Easy difficulty, 2 are Medium, and 0 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 3 reported problems, DeltaX interviews are easier than average - only 0% Hard compared to 18% across all companies. 67% of questions are Medium difficulty. Focus on the high-frequency Medium problems first, then work through the Hard ones.
Start with the highest-frequency problems listed on this page. Focus on the core topics: hash-table, math, string. Practice solving them under time pressure and explaining your approach out loud. Mock interviews with AI can simulate the real experience.
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