Coding interview questions

Oracle Coding Interview Questions (DSA)

The 50 DSA problems Oracle has asked most in the last six months, most-asked first. 50 of them have a full breakdown with diagrams and code. Tick them off as you go.

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50problems
50full breakdowns
38topics

By difficulty: Easy (8) · Medium (37) · Hard (5)

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Topics

18.4Sum
Full breakdownArrayTwo PointersSorting
Medium▶ Mock
1.Two Sum
Full breakdownArrayHash Table
Easy+10▶ Mock
23.Merge k Sorted Lists
Full breakdownLinked ListDivide and ConquerHeap (Priority Queue)
Hard+4▶ Mock
33.Search in Rotated Sorted Array
Full breakdownArrayBinary Search
Medium+5▶ Mock
721.Accounts Merge
Full breakdownArrayHash TableString
Medium▶ Mock
200.Number of Islands
Full breakdownArrayDepth-First SearchBreadth-First Search
Medium+7▶ Mock
981.Time Based Key-Value Store
Full breakdownHash TableStringBinary Search
Medium+1▶ Mock
76.Minimum Window Substring
Full breakdownHash TableStringSliding Window
49.Group Anagrams
Full breakdownArrayHash TableString
Medium+9▶ Mock
2.Add Two Numbers
Full breakdownLinked ListMathRecursion
Medium+3▶ Mock
3.Longest Substring Without Repeating Characters
Full breakdownHash TableStringSliding Window
Medium+13▶ Mock
5.Longest Palindromic Substring
Full breakdownTwo PointersStringDynamic Programming
Medium+8▶ Mock
6.Zigzag Conversion
Full breakdownString
Medium▶ Mock
11.Container With Most Water
Full breakdownArrayTwo PointersGreedy
Medium+6▶ Mock
14.Longest Common Prefix
Full breakdownArrayStringTrie
Easy+1▶ Mock
17.Letter Combinations of a Phone Number
Full breakdownHash TableStringBacktracking
Medium+1▶ Mock
15.3Sum
Full breakdownArrayTwo PointersSorting
Medium+5▶ Mock
21.Merge Two Sorted Lists
Full breakdownLinked ListRecursion
Easy+2▶ Mock
22.Generate Parentheses
Full breakdownStringDynamic ProgrammingBacktracking
Medium+1▶ Mock
26.Remove Duplicates from Sorted Array
Full breakdownArrayTwo Pointers
Easy+1▶ Mock
41.First Missing Positive
Full breakdownArrayHash Table
42.Trapping Rain Water
Full breakdownArrayTwo PointersDynamic Programming
Hard+6▶ Mock
45.Jump Game II
Full breakdownArrayDynamic ProgrammingGreedy
Medium▶ Mock
46.Permutations
Full breakdownArrayBacktracking
Medium▶ Mock
50.Pow(x, n)
Full breakdownMathRecursion
Medium▶ Mock
48.Rotate Image
Full breakdownArrayMathMatrix
Medium▶ Mock
53.Maximum Subarray
Full breakdownArrayDivide and ConquerDynamic Programming
Medium+8▶ Mock
54.Spiral Matrix
Full breakdownArrayMatrixSimulation
Medium+2▶ Mock
55.Jump Game
Full breakdownArrayDynamic ProgrammingGreedy
Medium▶ Mock
56.Merge Intervals
Full breakdownArraySortingQuicksort
Medium+14▶ Mock
57.Insert Interval
Full breakdownArray
Medium▶ Mock
73.Set Matrix Zeroes
Full breakdownArrayHash TableMatrix
Medium▶ Mock
75.Sort Colors
Full breakdownArrayTwo PointersSorting
Medium▶ Mock
79.Word Search
Full breakdownArrayStringBacktracking
Medium+1▶ Mock
74.Search a 2D Matrix
Full breakdownArrayBinary SearchMatrix
Medium▶ Mock
88.Merge Sorted Array
Full breakdownArrayTwo PointersSorting
Easy+1▶ Mock
93.Restore IP Addresses
Full breakdownStringBacktracking
Medium▶ Mock
98.Validate Binary Search Tree
Full breakdownTreeDepth-First SearchBinary Search Tree
Medium+4▶ Mock
103.Binary Tree Zigzag Level Order Traversal
Full breakdownTreeBreadth-First SearchBinary Tree
Medium▶ Mock
Populating Next Right Pointers in Each Node
Full breakdownLinked ListTreeDepth-First Search
Medium+2▶ Mock
121.Best Time to Buy and Sell Stock
Full breakdownArrayDynamic Programming
Easy+10▶ Mock
128.Longest Consecutive Sequence
Full breakdownArrayHash TableUnion-Find
Medium+3▶ Mock
134.Gas Station
Full breakdownArrayGreedy
Medium+6▶ Mock
138.Copy List with Random Pointer
Full breakdownHash TableLinked List
Medium+1▶ Mock
140.Word Break II
Full breakdownArrayHash TableString
141.Linked List Cycle
Full breakdownHash TableLinked ListTwo Pointers
146.LRU Cache
Full breakdownHash TableLinked ListDesign
Medium+10▶ Mock
155.Min Stack
Full breakdownStackDesign
Medium▶ Mock
169.Majority Element
Full breakdownArrayHash TableDivide and Conquer

Frequently Asked Questions

What questions does Oracle ask in coding interviews?

Oracle coding interviews focus on Array, Backtracking, Binary Search, Binary Search Tree, and other data structure problems. We compiled 50 questions from real Oracle interviews. The most common topics are Array, Backtracking, Binary Search, Binary Search Tree, Binary Tree. Filter by topic to see what comes up most often.

How many Oracle coding interview questions are there?

InterviewSkool has 50 Oracle coding interview questions: 8 Easy, 37 Medium, and 5 Hard. Most Oracle interviews focus on Medium-difficulty problems, so prioritize those in your prep.

How should I prepare for Oracle coding interviews?

Start with Medium difficulty problems. Group by topic (Array, Tree, DP) to build pattern recognition. Aim to solve 30 to 40 problems before your interview. Then practice under pressure with a mock interview.

Are Oracle coding interview questions free?

Yes. All 50 Oracle coding interview questions are free to browse with no sign-up required. You can filter by difficulty and topic tags. Start a mock interview with a free credit to practice under real pressure.

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