Oracle Coding & Algorithms Interview Questions
Practice the exact questions companies are asking right now.
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Solve Five Coding Problems
The interview included several coding tasks. Solve each of the following and discuss time and space complexity: 1. Given a 2D grid where '1' represent...
Compute letter frequencies from encoded string
Problem You are given an encoded string s representing a string of lowercase English letters (a–z). The encoding follows these rules: 1. Letters a to ...
Return a valid course completion order
You are given an integer n representing n courses labeled 0..n-1 and a list of prerequisite pairs prerequisites, where each pair [a, b] means you must...
Implement in-memory data structures and booking API
Part A — Implement a simplified Redis-like in-memory store (Go) Implement an in-memory key-value store that supports string values and list-of-strings...
Count closed islands in a grid
Problem You are given an m x n 2D grid representing a map after flooding: - 0 = water - 1 = land An island is a maximal 4-directionally connected comp...
Implement an LRU cache
Design and implement a data structure for a Least Recently Used (LRU) cache with a fixed capacity. The cache must support: - get(key): return the valu...
Count Closed Islands
You are given an m x n binary grid representing terrain after flooding. - 0 = land - 1 = water A land region is an island if its land cells are connec...
Count Interior Islands After Flooding
You are given an m x n binary grid representing land and water. - 1 = land - 0 = water An island is a maximal group of land cells connected 4-directio...
Maximize area between vertical lines
Problem You are given an integer array h where h[i] represents the height of a vertical line drawn at x-coordinate i. Choose two different indices i <...
Count Enclosed Islands in a Grid
You are given an m x n grid representing land and water after flooding. - 0 represents land. - 1 represents water. - Two land cells belong to the same...
Find users with at least one valid session
You are given: - A list of log entries logs, where each entry is a string in the format: ` "userId action timestamp" ` - userId is a non...
Implement an LRU cache
Design and implement an in-memory cache that evicts entries using the Least Recently Used (LRU) policy. The cache should store key–value pairs and sup...
Minimize sum with halving operations
You are given an array of non-negative integers nums and an integer k. In one operation, choose any index i and replace nums[i] with ceil(nums[i] / 2)...
Count anagram-based replacements per phrase
Problem You are given: - phrases: a list of strings, where each string is a phrase containing words separated by single spaces. - words: a list of str...
Solve three DSA problems: trie, window, intervals
1) Design and implement an autocomplete service. Support insert(word) to add a word and suggest(prefix) to return up to five existing words that start...
Find shortest subarray meeting target sum
Given an integer array nums (values may be negative) and an integer T, return the length of the shortest non-empty contiguous subarray whose sum is at...
Determine if robot path is bounded
A robot starts at (0, 0) facing North on an infinite grid. It executes a string s consisting of 'G' (move forward 1 unit), 'L' (turn left 90°), and 'R...
Design structure for first unique login user
You are given an online stream of user login events. Each event is a user ID (e.g., an integer or string) indicating that this user has just logged in...