Problem database last updated: June 20, 2025
6 problems · 1 Easy, 4 Medium, 1 Hard · Ranked #210 of 458
1 Easy
17% · avg 23%
4 Medium
67% · avg 59%
1 Hard
17% · avg 18%
Based on 6 reported problems, Nielsen interviews are in line with industry averages - 17% Hard vs 18% overall. 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, Nielsen puts unusual emphasis on dynamic-programming (50% of problems, 2.5x the industry average), sorting (33.3% of problems, 2.3x the industry average), string (50% of problems, 1.8x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are array (66.7%), string (50%), dynamic-programming (50%), sorting (33.3%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Longest Palindromic Substring Given a string s, return the longest palindromic substring in s. | Medium | Very Likely | two-pointersstringdynamic-programming | Solve |
Group Anagrams Given an array of strings strs, group the anagrams together. You can return the answer in any order. | Medium | Very Likely | arrayhash-tablestring | Solve |
Two Sum Given an array of integers nums and an integer target, return the indices of the two numbers that add up to target. | Easy | Very Likely | arrayhash-map | Solve |
Merge Intervals Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cove... | Medium | Very Likely | arraysorting | Solve |
Edit Distance Given two strings word1 and word2, return the minimum number of operations required to convert word1 to word2. | Medium | Very Likely | stringdynamic-programming | Solve |
Best Time to Buy and Sell Stock IV You are given an integer array prices where prices[i] is the price of a given stock on the ith day, and an integer k. | Hard | Very Likely | arraydynamic-programming | Solve |
Longest Palindromic Substring
SolveGiven a string s, return the longest palindromic substring in s.
Group Anagrams
SolveGiven an array of strings strs, group the anagrams together. You can return the answer in any order.
Two Sum
SolveGiven an array of integers nums and an integer target, return the indices of the two numbers that add up to target.
Merge Intervals
SolveGiven an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cove...
Edit Distance
SolveGiven two strings word1 and word2, return the minimum number of operations required to convert word1 to word2.
Best Time to Buy and Sell Stock IV
SolveYou are given an integer array prices where prices[i] is the price of a given stock on the ith day, and an integer k.
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent Nielsen interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
Nielsen interviews focus heavily on array, string, dynamic-programming 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. Nielsen 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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Nielsen has been reported to ask 6 distinct coding problems. The most common topics are array, string, dynamic-programming. 1 are Easy difficulty, 4 are Medium, and 1 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 6 reported problems, Nielsen interviews are in line with industry averages - 17% Hard vs 18% overall. 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: array, string, dynamic-programming. 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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