Duolingo Coding Interview Questions
We track 5 coding questions asked at Duolingo, tagged with the algorithms and concepts they test. The most common: Array, Hash Table, Breadth-First Search, Depth-First Search, Design.
Browse all 5 Duolingo questions →Concept mix
Each question's weight is split evenly across its concepts, so the shares sum to 100%.
- Array29.8%
- Hash Table17.3%
- Sliding Window10.0%
- Greedy6.7%
- Simulation6.7%
- Design4.0%
- String4.0%
- Trie4.0%
- Breadth-First Search2.5%
- Depth-First Search2.5%
- Other (5)12.5%
How many questions involve each concept
Share of all 5 tracked Duolingo questions that touch each concept. Questions usually involve several, so these overlap.
- Array100.0%
- Hash Table60.0%
- Breadth-First Search20.0%
- Depth-First Search20.0%
- Design20.0%
- Dynamic Programming20.0%
- Graph Theory20.0%
- Greedy20.0%
- Matrix20.0%
- Memoization20.0%
- Simulation20.0%
- Sliding Window20.0%
Where Duolingo differs from the average company
Concept weight at Duolingo relative to the average across all companies we track. Green means Duolingo leans on it harder than most.
- Hash Table2.6×
- Array1.5×
Duolingo specialties
Concepts that show up at Duolingo but are rarely asked elsewhere. They are easy to get blindsided by.
Difficulty mix
Level split of the 5 tracked Duolingo questions.
- Mid/Senior60% (3)
- Staff40% (2)
Every concept in Duolingo interviews
| Concept | Questions | % of questions | Share of mix |
|---|---|---|---|
| Array | 5 | 100.0% | 29.8% |
| Hash Table | 3 | 60.0% | 17.3% |
| Breadth-First Search | 1 | 20.0% | 2.5% |
| Depth-First Search | 1 | 20.0% | 2.5% |
| Design | 1 | 20.0% | 4.0% |
| Dynamic Programming | 1 | 20.0% | 2.5% |
| Graph Theory | 1 | 20.0% | 2.5% |
| Greedy | 1 | 20.0% | 6.7% |
| Matrix | 1 | 20.0% | 2.5% |
| Memoization | 1 | 20.0% | 2.5% |
| Simulation | 1 | 20.0% | 6.7% |
| Sliding Window | 1 | 20.0% | 10.0% |
| String | 1 | 20.0% | 4.0% |
| Topological Sort | 1 | 20.0% | 2.5% |
| Trie | 1 | 20.0% | 4.0% |
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