JetBrains Coding Interview Questions
25 JetBrains coding interview problems with full optimal solutions — 9 easy, 12 medium, 4 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an JetBrains interviewer values, and a FAQ section.
Showing 9 problems of 25
- #1easyfoundational
1. Two Sum
Find two indices whose values sum to a target, used at JetBrains to gauge baseline data-structure fluency before symbol-table style problems.
- #2easyfoundational
2. Valid Parentheses
Determine if a string of brackets is balanced — the bread-and-butter check inside every JetBrains parser before AST construction.
- #3easyfoundational
3. Same Tree
Check whether two binary trees are structurally and value-equal node-by-node — JetBrains uses this to gauge whether you can compare PSI subtrees for incremental reparse.
- #4easyfoundational
4. Best Time to Buy and Sell Stock
Find the max profit from one buy and one sell over a price array — a single-pass scan that mirrors the streaming token analyses inside JetBrains lexers.
- #5easyfoundational
5. Single Number
Find the one element that appears once when all others appear twice — JetBrains uses this to test XOR fluency, a primitive in their hash-based PSI fingerprints.
- #5easyfoundational
5. Valid Palindrome
Check whether a sanitized string reads identically forward and backward — JetBrains uses this to gauge two-pointer discipline before deeper string-scanning problems.
- #6easyfoundational
6. Linked List Cycle
Detect whether a linked list contains a cycle — JetBrains uses this to gauge whether you can spot graph cycles in symbol-resolution chains.
- #7easyfoundational
7. Min Stack
Design a stack supporting push/pop/top/getMin all in O(1) — JetBrains uses this to gauge whether you can maintain auxiliary invariants in scope-stack data structures.
- #8easyfoundational
8. Majority Element
Find the element that appears more than n/2 times — JetBrains uses this to test whether you can collapse counters in constant space using the Boyer-Moore vote.