Meta Coding Interview Questions
32 Meta coding interview problems with full optimal solutions — 5 easy, 23 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 Meta interviewer values, and a FAQ section.
Showing 23 problems of 32
- #21mediumfoundational
21. Number of Islands
Count connected land regions in a 2D grid — Meta uses this BFS/DFS pattern directly in social-graph clustering and detecting connected communities in their global friend network.
- #22mediumfoundational
22. Clone Graph
Deep-copy an undirected graph — Meta's social network literally deep-copies subgraph views for privacy sandboxing, making this BFS/DFS-with-hash-map pattern a genuine engineering analog used in production systems.
- #23mediumfoundational
23. K Closest Points to Origin
Find the k nearest geographic points to a center — Meta's location-based friend discovery and venue recommendations run exactly this top-K proximity filter at massive scale every second across billions of location signals.
- #24mediumfoundational
24. Merge Intervals
Collapse overlapping time windows into a minimal set — Meta's event-scheduling system, ad-slot deduplication, and calendar integrations all rely on this interval-merge pattern at their core.
- #28mediumfoundational
28. Decode Ways
Count ways to decode a digit string into letters — Meta's notification encoding and push-message compression pipelines use DP-based decoding to count valid parse paths through variable-length encoded payloads at scale.
- #31mediumfoundational
31. Find All Anagrams in a String
Find every starting index where a pattern's anagram appears in text — Meta's content-search and hashtag-matching pipelines use this sliding-window frequency-map pattern to surface variations without expensive sort-based comparisons.
- #32mediumfoundational
32. Binary Tree Right Side View
Return the last visible node at each tree level — Meta's comment-threading UI renders the rightmost visible reply at each nesting depth, and feed-ranking previews use this BFS level-order traversal pattern to surface the most prominent item per tier.
- #50mediumfrequently asked
50. Pow(x, n)
Compute x raised to the n-th power. Meta asks this to test whether you reach for the O(log n) fast-exponentiation pattern and can handle the negative exponent edge case.
- #71mediumfrequently asked
71. Simplify Path
Given an absolute Unix-style path, return the canonical simplified form. Meta asks this to test whether you reach for stack-based processing of path segments and handle the '..', '.', and consecutive-slash edge cases correctly.
- #138mediumfrequently asked
138. Copy List With Random Pointer
Deep-copy a linked list where each node has a random pointer in addition to next. Meta asks this to test whether you can handle the two-pass map approach or the elegant O(1)-space interleaving trick.
- #215mediumfrequently asked
215. Kth Largest Element in an Array
Return the k-th largest element in an unsorted array. Meta asks this to test whether you reach for a min-heap of size k or quickselect, and can articulate the n log k vs O(n) average tradeoff.
- #227mediumfrequently asked
227. Basic Calculator II
Evaluate a string expression with +, -, *, / and non-negative integers. Meta asks this to test whether you reach for the stack-based delayed-add pattern that handles precedence without recursion or explicit token parsing.
- #236mediumfrequently asked
236. Lowest Common Ancestor of a Binary Tree
Given a binary tree, find the LCA of two nodes. Meta asks this to test whether you grasp the canonical postorder recursion: 'if I find p in one subtree and q in the other, I'm the LCA.'
- #314mediumcompany favorite
314. Binary Tree Vertical Order Traversal
Given a binary tree, return its vertical order traversal of node values. Meta asks this to test whether you reach for BFS with column tracking (so left children get column - 1 and right children get column + 1).
- #523mediumfrequently asked
523. Continuous Subarray Sum
Given an array and integer k, return true if there's a contiguous subarray of size at least 2 whose sum is a multiple of k. Meta asks this to test whether you reach for prefix sums + mod and articulate the 'same remainder means divisible difference' trick.
- #528mediumcompany favorite
528. Random Pick With Weight
Given a positive-integer weights array, implement pickIndex() that returns i with probability proportional to w[i]. Meta asks this to test whether you reach for prefix sums + binary search and can articulate the uniform-random-on-[0, total) framing.
- #560mediumfrequently asked
560. Subarray Sum Equals K
Given an integer array and integer k, return the count of contiguous subarrays whose sum equals k. Meta asks this to test whether you reach for the prefix-sum + hash map pattern and articulate the 'count[prefixSum - k]' trick.
- #670mediumfrequently asked
670. Maximum Swap
Given a non-negative integer, you may swap two digits at most once to get the maximum valued number. Meta asks this to test whether you reach for the 'find largest later digit to swap with earliest smaller digit' greedy.
- #721mediumfrequently asked
721. Accounts Merge
Given accounts with emails, merge accounts that share any email (transitively). Meta asks this to test whether you reach for union-find or BFS/DFS on an implicit graph and articulate the connected-components framing.
- #986mediumfrequently asked
986. Interval List Intersections
Given two sorted lists of disjoint intervals, return the intersection. Meta asks this to test whether you reach for the two-pointer pattern and articulate why it's O(m+n) instead of O(m*n).
- #1091mediumfrequently asked
1091. Shortest Path in Binary Matrix
Find the shortest path in a binary matrix from top-left to bottom-right, moving through 0-cells in 8 directions. Meta asks this to test whether you reach for BFS for shortest-path on unweighted grids.
- #1249mediumcompany favorite
1249. Minimum Remove to Make Valid Parentheses
Given a string with letters and parens, remove the minimum number of parens to make it valid. Meta asks this to test whether you can identify removals in a single stack pass (forward + backward sweeps work too).
- #1762mediumcompany favorite
1762. Buildings With an Ocean View
Given building heights, return indices that can see the ocean to the right. Meta asks this to test whether you reach for the right-to-left sweep that's O(n), not the O(n^2) per-building lookahead.
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