Problem database last updated: June 20, 2025
2 problems · 0 Easy, 2 Medium, 0 Hard · Ranked #374 of 458
0 Easy
0% · avg 23%
2 Medium
100% · avg 59%
0 Hard
0% · avg 18%
Based on 2 reported problems, Alibaba interviews are easier than average - only 0% Hard compared to 18% across all companies. The majority (100%) 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, Alibaba puts unusual emphasis on string (100% of problems, 3.6x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are string (100%), dynamic-programming (50%), stack (50%), greedy (50%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Valid Parenthesis String Given a string s containing only three types of characters: '(', ')' and '', return true if s is valid. | Medium | Very Likely | stringdynamic-programmingstack | Solve |
Longest Substring Without Repeating Characters Given a string s, find the length of the longest substring without duplicate characters. | Medium | Likely | hash-tablestringsliding-window | Solve |
Valid Parenthesis String
SolveGiven a string s containing only three types of characters: '(', ')' and '', return true if s is valid.
Longest Substring Without Repeating Characters
SolveGiven a string s, find the length of the longest substring without duplicate characters.
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent Alibaba interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
Alibaba interviews focus heavily on string, dynamic-programming, stack 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. Alibaba 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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Alibaba has been reported to ask 2 distinct coding problems. The most common topics are string, dynamic-programming, stack. 0 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 2 reported problems, Alibaba interviews are easier than average - only 0% Hard compared to 18% across all companies. 100% 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: string, dynamic-programming, stack. 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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