Atlassian Coding Interview Questions
25 Atlassian coding interview problems with full optimal solutions — 4 easy, 18 medium, 3 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an Atlassian interviewer values, and a FAQ section.
Showing 18 problems of 25
- #3mediumfrequently asked
3. Longest Substring Without Repeating Characters
Longest Substring Without Repeating Characters is the canonical Atlassian sliding-window problem. Given a string s, return the length of the longest substring without repeating characters. Atlassian uses it to gate whether you understand the two-pointer / sliding-window pattern.
4 free resourcesSolve → - #49mediumfrequently asked
49. Group Anagrams
Group Anagrams is an Atlassian favorite because it mirrors the bucket-by-canonical-key idea behind Confluence search and Jira tag dedupe. You're given an array of strings; return the strings grouped so each group contains anagrams of one another.
3 free resourcesSolve → - #56mediumcompany favorite
56. Merge Intervals
Merge Intervals is an Atlassian-favorite scheduling problem. Given an array of intervals [start, end], merge all overlapping ones and return the result. It maps directly to calendar coalescing in Atlassian's Confluence calendars and Jira time-tracking UIs.
4 free resourcesSolve → - #79mediumfrequently asked
79. Word Search
Word Search is an Atlassian DFS-backtracking problem. Given a grid of characters and a target word, return true if the word can be constructed from adjacent (horizontal/vertical) letters with no cell reused. Atlassian uses it to check whether you can write backtracking that cleans up after itself.
4 free resourcesSolve → - #98mediumfrequently asked
98. Validate Binary Search Tree
Validate Binary Search Tree is an Atlassian classic for testing whether you understand the recursive invariant of a BST. Return true if a given binary tree is a valid BST. The naive 'check children' answer is wrong, and Atlassian uses this exact gap to grade rigorous thinkers.
4 free resourcesSolve → - #102mediumfrequently asked
102. Binary Tree Level Order Traversal
Binary Tree Level Order Traversal is the canonical Atlassian BFS-on-a-tree problem. Return the nodes' values level by level (left to right, one array per level). Atlassian uses it to confirm you can write BFS without smearing levels together.
4 free resourcesSolve → - #139mediumfrequently asked
139. Word Break
Word Break is an Atlassian-favorite dynamic programming problem. Given a string s and a dictionary, determine whether s can be segmented into a space-separated sequence of dictionary words. Atlassian uses it to test memoization intuition before harder string-DP follow-ups.
4 free resourcesSolve → - #146mediumcompany favorite
146. LRU Cache
LRU Cache is Atlassian's classic OOP-and-data-structure design problem. Design a fixed-capacity cache that evicts the least-recently-used key on overflow with O(1) get and put. Atlassian asks it to test whether you can combine a doubly-linked list with a hash map without dropping pointer invariants under pressure.
4 free resourcesSolve → - #200mediumfrequently asked
200. Number of Islands
Number of Islands is Atlassian's canonical grid-graph problem. Given an m x n grid of '1' (land) and '0' (water), return the number of distinct land islands. Atlassian asks it because grid traversal under-pressure is a clean signal for whether you can navigate Jira's board layouts or Confluence's page trees.
4 free resourcesSolve → - #207mediumcompany favorite
207. Course Schedule
Course Schedule is an Atlassian-favorite graph problem because it mirrors Jira's dependency model. Given numCourses and a list of prerequisite pairs, determine whether you can finish all courses — equivalent to detecting a cycle in a directed graph.
4 free resourcesSolve → - #208mediumcompany favorite
208. Implement Trie (Prefix Tree)
Implement Trie is an Atlassian-favorite OOP-design problem because tries power Confluence's @-mention autocomplete and Jira's smart label search. You design a prefix tree supporting insert, search (full word), and startsWith (prefix). The grading focus is clean class structure and pointer ownership.
4 free resourcesSolve → - #215mediumfrequently asked
215. Kth Largest Element in an Array
Kth Largest Element in an Array is an Atlassian heap-vs-quickselect classic. Given an integer array and an integer k, return the kth largest element. The grading is whether you can compare the heap, sort, and quickselect tradeoffs without hand-waving.
4 free resourcesSolve → - #253mediumcompany favorite
253. Meeting Rooms II
Meeting Rooms II is an Atlassian-favorite resource-allocation problem. Given an array of meeting time intervals, return the minimum number of rooms required so every meeting can run without conflicts. It maps directly to Atlassian's Confluence team-calendar scheduler.
4 free resourcesSolve → - #322mediumfrequently asked
322. Coin Change
Coin Change is an Atlassian-favorite dynamic programming problem. Given coin denominations and a target amount, return the fewest coins needed to make the amount, or -1 if impossible. Atlassian asks it because the bottom-up DP solution is a clean signal for whether you can write a tabular DP from a recurrence.
4 free resourcesSolve → - #347mediumfrequently asked
347. Top K Frequent Elements
Top K Frequent Elements is Atlassian's heap-and-counting interview classic. Given an integer array and an integer k, return the k most frequent elements. Atlassian asks it because top-k ranking is the algorithmic backbone behind Confluence's 'most active pages' and Jira's 'top reporters' surfaces.
4 free resourcesSolve → - #348mediumcompany favorite
348. Design Tic-Tac-Toe
Design Tic-Tac-Toe is Atlassian's OOP-design problem. Implement a game where two players take turns marking cells; the move method returns the current player's win state. The grading focus is O(1) per move using per-row, per-column, and diagonal counters — not a full board scan.
4 free resourcesSolve → - #560mediumfrequently asked
560. Subarray Sum Equals K
Subarray Sum Equals K is an Atlassian-favorite prefix-sum + hash-map problem. Given an integer array and an integer k, return the total number of subarrays whose sum equals k. The unsigned reveal is that prefix sums + hash map is the optimal — sliding window fails when negatives appear.
4 free resourcesSolve → - #973mediumfrequently asked
973. K Closest Points to Origin
K Closest Points to Origin is Atlassian's canonical heap-introduction problem. Given an array of points and an integer k, return the k points closest to (0,0) by Euclidean distance. Atlassian uses it as the first step toward more complex top-k ranking systems in their search UI.
4 free resourcesSolve →
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