LinkedIn Coding Interview Questions
32 LinkedIn coding interview problems with full optimal solutions — 4 easy, 21 medium, 7 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an LinkedIn interviewer values, and a FAQ section.
Showing 21 problems of 32
- #56mediumfoundational
56. Merge Intervals
Merge all overlapping intervals in a list into non-overlapping ranges — LinkedIn uses this pattern to consolidate overlapping employment date ranges in member profiles and to compact calendar availability windows, making it one of the most practically grounded problems in their interview bank.
- #91mediumfoundational
91. Decode Ways
Count the number of ways to decode a digit string where each letter maps to 1–26 — LinkedIn asks this DP problem to test whether you can enumerate valid interpretation paths under constraints, the same combinatorial reasoning used in their NLP pipeline for ambiguous entity recognition in profile text.
- #133mediumfoundational
133. Clone Graph
Deep-copy a connected undirected graph using BFS and a hash map — a near-literal model of how LinkedIn clones member connection graphs across data centers, making it one of the most contextually on-brand questions in their rotation.
- #199mediumfoundational
199. Binary Tree Right Side View
Return the values visible when looking at a binary tree from the right side — LinkedIn applies this BFS-by-level pattern to render hierarchical org-chart data, surfacing only the rightmost node at each reporting tier, a frequent warm-up before harder tree design questions.
- #200mediumfoundational
200. Number of Islands
Count connected landmasses in a grid using BFS or DFS — LinkedIn uses this to probe how you think about connected-component discovery, the same graph reasoning behind mapping professional networks and finding isolated clusters in the member graph.
- #207mediumfoundational
207. Course Schedule
Determine if a set of courses with prerequisites can all be finished — this is cycle detection on a directed graph, the exact algorithm LinkedIn runs to validate skill-path dependency chains and surface circular credential requirements in their learning platform.
- #238mediumfoundational
238. Product of Array Except Self
Compute the product of every array element except the current one — without division — using prefix and suffix passes. LinkedIn asks this to test whether you can reason about O(n) algorithms under artificial constraints, mirroring how their data pipeline computes per-member aggregates that exclude the member's own data.
- #253mediumfoundational
253. Meeting Rooms II
Find the minimum number of meeting rooms needed to schedule all intervals without overlap — LinkedIn applies this algorithm to allocate recruiter calendar slots and to detect overlapping employment periods in member profiles, one of their most-cited interval problems.
- #347mediumfoundational
347. Top K Frequent Elements
Return the k most frequent elements from an array — this is the algorithm behind LinkedIn's 'People You May Know' ranking and trending job suggestion surfaces, where you need the top-K signals from a frequency count without sorting the entire dataset.
- #47mediumfrequently asked
47. Permutations II
Given a collection of integers (possibly with duplicates), return all unique permutations. LinkedIn asks this on the backtracking round — they want the sort-then-skip-duplicates pattern, not generate-then-dedupe.
4 free resourcesSolve → - #150mediumcompany favorite
150. Evaluate Reverse Polish Notation
Given an array of tokens in Reverse Polish (postfix) notation, evaluate and return the result. LinkedIn asks this because it's the textbook stack problem — they want clean push-on-operand, pop-pop-apply-push-on-operator without any parsing distractions.
4 free resourcesSolve → - #152mediumfrequently asked
152. Maximum Product Subarray
Given an integer array, find the contiguous subarray with the largest product. LinkedIn asks this on the DP round because negatives turn Kadane on its head — you need to track BOTH min and max running products to handle sign flips.
4 free resourcesSolve → - #208mediumcompany favorite
208. Implement Trie (Prefix Tree)
Implement a Trie with insert, search, and startsWith. LinkedIn asks this because it's the foundation of their typeahead and autocomplete features — they want a clean node-with-children-map structure and the isEnd boolean.
4 free resourcesSolve → - #230mediumfrequently asked
230. Kth Smallest Element in a BST
Given a BST and integer k, return the kth smallest value. LinkedIn asks this on the BST round — they want the iterative inorder with early-stop, AND the follow-up answer if the tree is modified frequently (augment with subtree size).
4 free resourcesSolve → - #244mediumcompany favorite
244. Shortest Word Distance II
Same as Shortest Word Distance but with many queries. LinkedIn asks this to test whether you can amortize cost across queries — pre-bucket indices by word, then run a merge-like two-pointer walk per query.
4 free resourcesSolve → - #245mediumcompany favorite
245. Shortest Word Distance III
Same as Shortest Word Distance but word1 might equal word2 — meaning you need the closest pair of occurrences of the same word. LinkedIn asks this as the culminating follow-up to the series, testing whether you spot the asymmetric case before writing code.
4 free resourcesSolve → - #277mediumcompany favorite
277. Find the Celebrity
Given n people and a knows(a, b) API, find THE celebrity — someone known by everyone but who knows no one. LinkedIn asks this because it's the canonical 'elimination by partial order' problem — n calls find a candidate, n calls verify.
4 free resourcesSolve → - #339mediumcompany favorite
339. Nested List Weight Sum
Given a nested list of integers, return the sum of all integers weighted by their depth. LinkedIn asks this on the recursion round — they want clean DFS or BFS code that uses the provided NestedInteger interface without unpacking it eagerly.
4 free resourcesSolve → - #364mediumcompany favorite
364. Nested List Weight Sum II
Same as Nested List Weight Sum but the weighting is INVERTED — deepest leaves are weight 1 and the root is the heaviest. LinkedIn asks this as the trickier follow-up; the clean solution is a 'cumulative sum at each depth' trick that avoids two passes.
4 free resourcesSolve → - #366mediumcompany favorite
366. Find Leaves of Binary Tree
Given a binary tree, collect its leaves and remove them, then repeat. Return the order of removals. LinkedIn asks this because the elegant solution isn't iterative removal — it's a 'height from leaf' DFS that buckets each node by its eventual removal layer.
4 free resourcesSolve → - #797mediumfrequently asked
797. All Paths From Source to Target
Given a DAG with n nodes labeled 0 to n-1, find all possible paths from node 0 to node n-1. LinkedIn asks this on the graph traversal round — they want clean DFS with path tracking, no DP needed (because it's a DAG and paths could be exponential).
4 free resourcesSolve →
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