Dell coding interview
questions, leaked.
7 problems reported across recent Dell interviews. Top patterns: string, hash table, database. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Dell's interview loop hits you with 7 problems across a wide range of patterns, but string problems dominate the list. You're looking at 4 string-focused questions, which means you can't fake your way through substring logic, anagram patterns, or palindrome handling. Two are easy, three medium, two hard. The difficulty spread is deceptive. Most candidates focus on arrays and dynamic programming first. That's a mistake here. String manipulation and hash-table lookups are what you'll see first, and if you blank mid-assessment, StealthCoder surfaces the solution invisibly while you're screen-sharing.
Top problems at Dell
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Group Anagrams | MEDIUM | 100.0 | 71% | Array · Hash Table · String |
| 02 | Valid Parentheses | EASY | 100.0 | 42% | String · Stack |
| 03 | Merge k Sorted Lists | HARD | 100.0 | 57% | Linked List · Divide and Conquer · Heap (Priority Queue) |
| 04 | Longest Substring Without Repeating Characters | MEDIUM | 100.0 | 37% | Hash Table · String · Sliding Window |
| 05 | Longest Palindromic Substring | MEDIUM | 87.6 | 36% | Two Pointers · String · Dynamic Programming |
| 06 | Delete Duplicate Emails | EASY | 87.6 | 64% | Database |
| 07 | Department Top Three Salaries | HARD | 87.6 | 58% | Database |
Frequencies derived from public community-tagged interview reports. Click a row to view on LeetCode.
You have a week, maybe less. You can't out-grind the list above. StealthCoder runs invisibly during the actual Dell OA. The proctor cannot see it. Screen share cannot detect it. Made for the engineer who has done the work but might still blank with a webcam pointed at him.
Get StealthCoder- string4 · 57%
- hash table2 · 29%
- database2 · 29%
- array1 · 14%
- sorting1 · 14%
- stack1 · 14%
- linked list1 · 14%
- divide and conquer1 · 14%
- heap priority queue1 · 14%
- merge sort1 · 14%
String problems appear in 4 of the 7 reported questions, covering anagrams, substrings, palindromes, and parentheses validation. Hash tables and arrays back most of these. The secondary cluster is database problems, which jump straight to hard: you need SQL window functions and GROUP BY logic to handle department salary ranking. If you haven't written real SQL lately, that's your blind spot. The remaining problems span linked lists, sorting, and merge patterns. Focus your first week on string manipulation with hash tables as your go-to data structure, then lock in SQL syntax. When you sit down for the live assessment, StealthCoder is your hedge for any pattern you didn't have time to drill or a SQL query you can't quite assemble under pressure.
Companies with similar patterns
If you prepped for Dell, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Dell.
Memorizing every problem above in a week is a fantasy. StealthCoder is the hedge: an AI overlay that's invisible during screen share. It reads the problem on screen and surfaces a working solution in under 2 seconds. Made for the engineer who has done the work but might still blank with a webcam pointed at him. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Dell interview FAQ
How many string problems should I drill before a Dell OA?+
Dell reports 4 string problems out of 7 total. Drill at least Group Anagrams, Longest Substring Without Repeating Characters, and Longest Palindromic Substring. Valid Parentheses is your easy win. That covers the frequency. Then move to hash tables.
Is SQL enough for Dell's database questions, or do I need to optimize?+
Both reported database problems are hard. Delete Duplicate Emails is standard GROUP BY, but Department Top Three Salaries requires window functions and dense ranking. Know DENSE_RANK() and partition syntax before the OA.
Should I study linked lists before the interview?+
Merge k Sorted Lists is reported as hard and appears once. It's lower frequency than strings. Get it on your radar in week two, but don't burn time on singly-linked-list basics if strings aren't solid yet.
What's the easiest problem to warm up with?+
Valid Parentheses and Delete Duplicate Emails are both easy. Parentheses gets you comfortable with stacks and string iteration under low pressure. Use it as your five-minute opener on assessment day.
How much time should I spend on dynamic programming?+
One reported problem, Longest Palindromic Substring, touches DP. If you're strong on two-pointer expansion logic, you can solve it without DP recurrence. Don't sacrifice string drilling for DP theory.