Meta software engineer interviews cover algorithms, data structures, system design, and coding problems drawn from real interview rounds.
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coding
Hard
Verified Question
#1
1. OA[CodeSignal] Cloud File Storage System
Category: Graph coding problem
Question Your task is to implement a simple in-memory cloud storage system that maps objects (files) to their metadata (name, size, etc.). You...
Input: Graph (nodes and edges)Output: Array
coding
Hard
Verified Question
#2
2. OA[CodeSignal] Design Banking System
Category: Graph coding problem
Question Design a banking system that supports account management, transactions, and various financial operations.
Input: Graph (nodes and edges)Output: Computed result
coding
Hard
Verified Question
#3
3. Minimum Prefix Subset
Category: Tree coding problem
Question Given a list of strings, find the minimum subset of prefixes that can represent the entire input set. A string is "represented" if it...
Input: Array of stringsOutput: Integer
coding
Hard
Verified Question
#4
4. OA[CodeSignal] In-Memory Database
Category: Graph coding problem
Description Implement a simplified in-memory database that supports record manipulation with various operations. The system should handle basic...
Input: Graph (nodes and edges)Output: Array
coding
Hard
Verified Question
#5
5. [CodeSignal] House Segments After Destruction
Category: Array coding problem
Question You are monitoring the building density in a district of houses. The district is represented as a number line, where each house is located...
Input: Array of integersOutput: Array
coding
Hard
Verified Question
#6
6. Expression Simplifier
Category: String coding problemGiven an algebraic expression string containing single lowercase-letter variables, the operators
+ and -, and parentheses ( and ), simplify...Input: StringOutput: Computed result
coding
Hard
tree
#1
1. Binary Tree Serialization — serialize and deserialize a binary tree
Background: At Meta, efficient data storage and retrieval are essential for features like News Feed and Messenger. Serializing a binary tree allows for easy transfer and storage of tree structures, especially those representing user relationships or posts.
Problem statement: Implement the methods
Function/class signature:
Problem statement: Implement the methods
serialize and deserialize that convert a binary tree into a single string representation and back again. The representation must be unique and should correctly reconstruct the original tree structure. You can use any traversal method. Function/class signature:
def serialize(root: Optional[TreeNode]) -> str:def deserialize(data: str) -> Optional[TreeNode]:
- Input:
root = [1,2,3,null,null,4,5] - Output:
"1,2,3,null,null,4,5" - Explanation: The binary tree is represented in a level-order format as a string.
- Input:
root = [1] - Output:
"1,null" - Explanation: A single-node tree is represented correctly.
- The tree will have between
0and10^4nodes. - The node values will be integers in the range
[-1000, 1000].
coding
Hard
graph
#2
2. [OA] Graph Traversal — Find shortest path for the Facebook Events navigation
This problem simulates navigation through Facebook Events. Efficient pathfinding is crucial for enhancing user experience in discovering events.
Given an undirected graph represented as an adjacency list, return the shortest path from node
Input:
Output:
Explanation: The shortest path from node
Input:
Output:
Given an undirected graph represented as an adjacency list, return the shortest path from node
start to node end.Example 1:Input:
edges = [[0, 1], [1, 2], [2, 3]], start = 0, end = 3Output:
[0, 1, 2, 3]Explanation: The shortest path from node
0 to node 3 is 0 -> 1 -> 2 -> 3.Example 2:Input:
edges = [[0, 1], [1, 2], [0, 2], [2, 3]], start = 0, end = 3Output:
[0, 2, 3]Constraints:1 <= edges.length <= 10^4- Each edge is a pair of distinct integers.
coding
Hard
sliding window
#3
3. [OA] Sliding Window — Find the longest substring containing at most two distinct characters for Facebook Messenger
This problem is important for optimizing the chat list experience in the Messenger app. By ensuring quick access to frequently used contacts, we can enhance user engagement.
Given a string
Input:
Output:
Explanation: The substring is "ece" which its length is
Input:
Output:
Explanation: The substring is "aabbb" which its length is
Given a string
s, find the length of the longest substring containing at most two distinct characters.Example 1:Input:
s = "eceba"Output:
3Explanation: The substring is "ece" which its length is
3.Example 2:Input:
s = "ccaabbb"Output:
5Explanation: The substring is "aabbb" which its length is
5.Constraints:1 <= s.length <= 10^5sconsists of English letters, digits, symbols, and spaces.
system design
Hard
caching
#4
4. [OA] LRU Cache — Implement the caching system for Instagram feed
Instagram relies on providing quick access to user feeds, which requires an efficient cache management system. Design an LRU Cache to ensure optimal performance.Class LRUCache:
Example 1:
Input:
Output:
LRUCache(int capacity): Initializes the cache with a positive sizecapacity.int get(int key): Returns the value of the key if the key exists, otherwise returns-1.void put(int key, int value): Update the value of the key if present, or add the key-value pair if not existing. When the cache reaches its capacity, it should invalidate the least recently used item before inserting a new item.
Example 1:
Input:
LRUCache(2); cache.put(1, 1); cache.put(2, 2); cache.get(1); cache.put(3, 3); cache.get(2); cache.put(4, 4); cache.get(1); cache.get(3); cache.get(4);Output:
1; -1; 3; 4Constraints:capacityis always positive and will not exceed1000- The operations
getandputwill always be called with valid keys.
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