Problem database last updated: June 20, 2025
5 problems · 1 Easy, 3 Medium, 1 Hard · Ranked #237 of 458
1 Easy
20% · avg 23%
3 Medium
60% · avg 59%
1 Hard
20% · avg 18%
Based on 5 reported problems, The Trade Desk interviews are in line with industry averages - 20% Hard vs 18% overall. The majority (60%) 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, The Trade Desk puts unusual emphasis on hash-table (60% of problems, 2.7x the industry average), string (60% of problems, 2.1x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are hash-table (60%), string (60%), array (40%), trie (20%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Find the Length of the Longest Common Prefix You are given two arrays with positive integers arr1 and arr2. | Medium | Very Likely | arrayhash-tablestring | Solve |
Best Time to Buy and Sell Stock You are given an array prices where prices[i] is the price of a given stock on the ith day. | Easy | Likely | arraydynamic-programming | Solve |
Basic Calculator II Given a string s which represents an expression, evaluate this expression and return its value. | Medium | Likely | mathstringstack | Solve |
LRU Cache Design a data structure that follows the constraints of a Least Recently Used (LRU) cache. | Medium | Likely | hash-tablelinked-listdesign | Solve |
Word Ladder A transformation sequence from word beginWord to word endWord using a dictionary wordList is a sequence of words beginWord -> s1 -> s2 -> ... -> sk such that: | Hard | Likely | hash-tablestringbreadth-first-search | Solve |
Find the Length of the Longest Common Prefix
SolveYou are given two arrays with positive integers arr1 and arr2.
Best Time to Buy and Sell Stock
SolveYou are given an array prices where prices[i] is the price of a given stock on the ith day.
Basic Calculator II
SolveGiven a string s which represents an expression, evaluate this expression and return its value.
LRU Cache
SolveDesign a data structure that follows the constraints of a Least Recently Used (LRU) cache.
Word Ladder
SolveA transformation sequence from word beginWord to word endWord using a dictionary wordList is a sequence of words beginWord -> s1 -> s2 -> ... -> sk such that:
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent The Trade Desk interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
The Trade Desk interviews focus heavily on hash-table, string, array 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. The Trade Desk 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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The Trade Desk has been reported to ask 5 distinct coding problems. The most common topics are hash-table, string, array. 1 are Easy difficulty, 3 are Medium, and 1 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 5 reported problems, The Trade Desk interviews are in line with industry averages - 20% Hard vs 18% overall. 60% 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, string, array. 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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