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Oracle Master DSA Sheet

This compilation contains exclusive, previously asked data structure and algorithm questions from real Oracle interviews. Focus on these core problem patterns to confidently tackle even the hardest interview challenges.

top-specificoracle-prep
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340
Longest Substring Of All Vowels in Order
Medium
Unique Binary Search Trees
Medium
Spiral Matrix
Medium
Asteroid Collision3 Months
Medium
Minimize Maximum of Array
Medium
Top K Frequent Words
Medium
Valid Parentheses3 Months
Easy
Min Stack3 Months
Medium
Avoid Flood in The City3 Months
Medium
Jump Game II
Medium
Max Stack
Hard
Minimum Number of Steps to Make Two Strings Anagram
Medium
Second Highest Salary6 Months
Medium
Make Array Non-decreasing or Non-increasing
Hard
Pancake Sorting
Medium
Reverse Linked List6 Months
Easy
Subarray Product Less Than K
Medium
Meeting Rooms II30 Days
Medium
Design Authentication Manager
Medium
Kth Smallest Element in a Sorted Matrix3 Months
Medium
Design HashMap6 Months
Easy
Open the Lock30 Days
Medium
Validate IP Address
Medium
Maximum Good People Based on Statements
Hard
Reformat Date
Easy
Count the Number of Infection Sequences6 Months
Hard
Zigzag Conversion
Medium
Course Schedule II3 Months
Medium
Find Common Characters
Easy
Maximize Greatness of an Array
Medium
Serialize and Deserialize Binary Tree
Hard
Maximum Depth of Binary Tree
Easy
Path Sum III
Medium
Clone Graph
Medium
Diameter of Binary Tree30 Days
Easy
Two Sum IV - Input is a BST
Easy
Alien Dictionary
Hard
Maximum Number of Non-overlapping Palindrome Substrings6 Months
Hard
Longest Palindromic Substring6 Months
Medium
Product of Array Except Self
Medium
Search Suggestions System
Medium
Merge Intervals
Medium
K Closest Points to Origin
Medium
Encode and Decode Strings
Medium
Trapping Rain Water3 Months
Hard
Invalid Transactions3 Months
Medium
Two City Scheduling
Medium
Time Based Key-Value Store3 Months
Medium
Climbing Stairs6 Months
Easy
Generate Parentheses
Medium
Next Permutation
Medium
Split Array Largest Sum
Hard
All Nodes Distance K in Binary Tree
Medium
Koko Eating Bananas6 Months
Medium
Kth Smallest Element in a BST6 Months
Medium
Copy List with Random Pointer6 Months
Medium
Longest Substring Without Repeating Characters3 Months
Medium
Pow(x, n)
Medium
Basic Calculator III
Hard
Count Ways To Build Good Strings
Medium
First Missing Positive
Hard
Calculate Amount Paid in Taxes
Easy
Task Scheduler
Medium
Basic Calculator II
Medium
My Calendar I
Medium
Sqrt(x)6 Months
Easy
Minimum Window Substring30 Days
Hard
Minimum Knight Moves
Medium
Find All Numbers Disappeared in an Array
Easy
Daily Temperatures
Medium
Wildcard Matching
Hard
Convert Binary Number in a Linked List to Integer3 Months
Easy
Rotate Image
Medium
Valid Sudoku
Medium
Regular Expression Matching
Hard
Number of Visible People in a Queue3 Months
Hard
Maximum Profit in Job Scheduling3 Months
Hard
Permutation in String
Medium
Largest Number
Medium
Capacity To Ship Packages Within D Days6 Months
Medium
Merge Sorted Array
Easy
String Compression
Medium
Longest Common Subsequence
Medium
Single Element in a Sorted Array6 Months
Medium
Basic Calculator
Hard
Non-overlapping Intervals
Medium
Bus Routes6 Months
Hard
Word Search II
Hard
Making A Large Island
Hard
Two Sum30 Days
Easy
Design Circular Queue
Medium
Combination Sum
Medium
Roman to Integer
Easy
Longest Valid Parentheses
Hard
LFU Cache3 Months
Hard
Number of Islands3 Months
Medium
Two Sum II - Input Array Is Sorted
Medium
Logger Rate Limiter6 Months
Easy
Count and Say
Medium
Design In-Memory File System6 Months
Hard
Find the Smallest Divisor Given a Threshold
Medium
Insert Interval
Medium
Binary Tree Cameras
Hard
Palindromic Substrings6 Months
Medium
Search a 2D Matrix II
Medium
Maximize Value of Function in a Ball Passing Game
Hard
Rotting Oranges6 Months
Medium
Backspace String Compare
Easy
Course Schedule3 Months
Medium
Single Number III
Medium
Maximal Square
Medium
Longest Common Prefix
Easy
Maximum Earnings From Taxi
Medium
Insert Delete GetRandom O(1)
Medium
Container With Most Water30 Days
Medium
Find Valid Pair of Adjacent Digits in String
Easy
Frog Jump
Hard
Minimum Edge Reversals So Every Node Is Reachable6 Months
Hard
Minimum Sideway Jumps
Medium
Restore IP Addresses
Medium
Set Matrix Zeroes
Medium
Minimum Cost Path with Edge Reversals3 Months
Medium
Search in Rotated Sorted Array3 Months
Medium
Remove K Digits
Medium
Collect Coins in a Tree
Hard
Count Binary Substrings6 Months
Easy
Move Zeroes
Easy
Linked List Cycle II
Medium
Reverse Words in a String6 Months
Medium
Maximum Subarray3 Months
Medium
Contains Duplicate
Easy
Count Vowel Substrings of a String
Easy
Decode String6 Months
Medium
Edit Distance
Medium
Word Ladder3 Months
Hard
LRU Cache30 Days
Medium
Trapping Rain Water II
Hard
Isomorphic Strings
Easy
Permutations6 Months
Medium
Binary Tree Right Side View
Medium
Best Time to Buy and Sell Stock II
Medium
Island Perimeter
Easy
Count Substrings Without Repeating Character
Medium
Contiguous Array6 Months
Medium
Valid Anagram6 Months
Easy
Median of Two Sorted Arrays3 Months
Hard
Pour Water
Medium
Minimum Remove to Make Valid Parentheses6 Months
Medium
Largest Rectangle in Histogram
Hard
Greatest Common Divisor of Strings
Easy
Integer to Roman
Medium
Decode Ways
Medium
Lucky Numbers in a Matrix
Easy
Word Break II
Hard
Multiply Strings
Medium
N-Queens
Hard
Leaf-Similar Trees
Easy
Diagonal Traverse6 Months
Medium
Reorder List
Medium
Delete Node in a BST6 Months
Medium
All Ancestors of a Node in a Directed Acyclic Graph
Medium
Max Consecutive Ones III
Medium
Simplify Path
Medium
Count Ways to Group Overlapping Ranges
Medium
Minimum One Bit Operations to Make Integers Zero6 Months
Hard
Subarray Sum Equals K
Medium
Longest Substring with At Most K Distinct Characters
Medium
Count the Number of Houses at a Certain Distance II
Hard
Maximum Profit From Trading Stocks6 Months
Medium
Add Two Numbers
Medium
Design Add and Search Words Data Structure
Medium
Letter Combinations of a Phone Number
Medium
Gas Station
Medium
Remove All Adjacent Duplicates in String II3 Months
Medium
Convert Binary Search Tree to Sorted Doubly Linked List
Medium
Find the Duplicate Number
Medium
Binary Tree Maximum Path Sum
Hard
Triangle
Medium
Implement Trie (Prefix Tree)6 Months
Medium
Count the Number of Houses at a Certain Distance I
Medium
Word Squares II
Medium
Count Distinct Numbers on Board
Easy
Subarrays with K Different Integers
Hard
Group Anagrams6 Months
Medium
Remove Linked List Elements
Easy
Minimum Absolute Difference6 Months
Easy
Sort Colors6 Months
Medium
Valid Palindrome6 Months
Easy
Majority Element3 Months
Easy
Remove Invalid Parentheses
Hard
Average Selling Price
Easy
Pairs of Songs With Total Durations Divisible by 60
Medium
Best Time to Buy and Sell Stock3 Months
Easy
Lowest Common Ancestor of a Binary Tree6 Months
Medium
Find All Duplicates in an Array
Medium
Top K Frequent Elements3 Months
Medium
Merge Two Sorted Lists6 Months
Easy
Minimize Length of Array Using Operations
Medium
Palindrome Number
Easy
Word Search
Medium
Number of Students Unable to Eat Lunch
Easy
Jump Game
Medium
3Sum6 Months
Medium
Rotate Array
Medium
Merge k Sorted Lists3 Months
Hard
HTML Entity Parser
Medium
The Maze II
Medium
Longest Increasing Subsequence
Medium
Number of Flowers in Full Bloom
Hard
Fraction to Recurring Decimal
Medium
Fizz Buzz
Easy
First Unique Character in a String
Easy
Remove Duplicate Letters
Medium
Sort Array by Increasing Frequency
Easy
Find Peak Element
Medium
Missing Number
Easy
Sort List6 Months
Medium
Vertical Order Traversal of a Binary Tree3 Months
Hard
Max Area of Island3 Months
Medium
Populating Next Right Pointers in Each Node
Medium
Find First and Last Position of Element in Sorted Array3 Months
Medium
Binary Tree Zigzag Level Order Traversal
Medium
Odd Even Linked List
Medium
Count Servers that Communicate
Medium
Count Pairs Of Similar Strings
Easy
Decrypt String from Alphabet to Integer Mapping6 Months
Easy
Maximum Number of Events That Can Be Attended6 Months
Medium
Meeting Rooms III6 Months
Hard
Reverse Vowels of a String
Easy
Word Break
Medium
Text Justification
Hard
Boundary of Binary Tree
Medium
Step-By-Step Directions From a Binary Tree Node to Another
Medium
Longest Mountain in Array3 Months
Medium
Divide Two Integers
Medium
Happy Number
Easy
Remove All Adjacent Duplicates In String
Easy
Integer to English Words6 Months
Hard
Find Minimum in Rotated Sorted Array
Medium
Sudoku Solver
Hard
Minimum Size Subarray Sum
Medium
Subsets
Medium
Merge Strings Alternately
Easy
Remove Nth Node From End of List
Medium
Longest Consecutive Sequence6 Months
Medium
Last Stone Weight
Easy
Number of Closed Islands6 Months
Medium
Reorganize String6 Months
Medium
Reverse Integer
Medium
Find Leaves of Binary Tree30 Days
Medium
Sliding Window Maximum6 Months
Hard
Add Strings
Easy
Find K Pairs with Smallest Sums
Medium
Next Greater Element I
Easy
Find the Winner of the Circular Game
Medium
Sort an Array
Medium
Add Two Numbers II3 Months
Medium
Design File System
Medium
Remove Duplicates from Sorted Array
Easy
Rotate String
Easy
Water and Jug Problem
Medium
Flatten Binary Tree to Linked List
Medium
House Robber
Medium
Path Sum II
Medium
Palindrome Linked List
Easy
Merge Operations to Turn Array Into a Palindrome
Medium
Number of Distinct Islands
Medium
Keys and Rooms
Medium
Minimum Cost to Make Array Equal
Hard
Next Greater Element III
Medium
3Sum Smaller
Medium
Kth Largest Element in an Array6 Months
Medium
Minimum Insertion Steps to Make a String Palindrome6 Months
Hard
Distinct Subsequences
Hard
Combination Sum II
Medium
Can Place Flowers
Easy
Consecutive Numbers Sum6 Months
Hard
Reverse Substrings Between Each Pair of Parentheses
Medium
Validate Binary Search Tree
Medium
Kill Process
Medium
Degree of an Array6 Months
Easy
Distance to a Cycle in Undirected Graph30 Days
Hard
Candy
Hard
Reverse Linked List II6 Months
Medium
Delete Node in a Linked List6 Months
Medium
Find Median from Data Stream
Hard
Unique Paths
Medium
Coin Change3 Months
Medium
Count Number of Nice Subarrays
Medium
Plates Between Candles
Medium
Design a Text Editor
Hard
Number of Music Playlists
Hard
Swapping Nodes in a Linked List
Medium
Minimum Number of Increments on Subarrays to Form a Target Array
Hard
Count Primes
Medium
Merge In Between Linked Lists6 Months
Medium
Binary Search
Easy
Kth Missing Positive Number3 Months
Easy
Get the Maximum Score
Hard
Merge Nodes in Between Zeros
Medium
Create Maximum Number
Hard
Evaluate Reverse Polish Notation6 Months
Medium
Maximum Size Subarray Sum Equals k
Medium
Bulb Switcher
Medium
Longest Palindrome
Easy
Minimum Array Sum6 Months
Medium
Remove Duplicates from Sorted List II
Medium
Rearranging Fruits
Hard
Linked List Cycle
Easy
Maximum Candies Allocated to K Children
Medium
Rotate List
Medium
Redundant Connection
Medium
Minimum Cost Homecoming of a Robot in a Grid
Medium
Cache With Time Limit
Medium
Shortest Path in a Grid with Obstacles Elimination
Hard
Letter Tile Possibilities
Medium
Minimum Operations to Halve Array Sum
Medium
Invert Binary Tree
Easy
Binary Tree Level Order Traversal II3 Months
Medium
Remove Duplicates from Sorted List
Easy
Sparse Matrix Multiplication
Medium
Swap Nodes in Pairs
Medium
Binary Tree Level Order Traversal3 Months
Medium
Count of Range Sum
Hard
Search a 2D Matrix
Medium
Counting Bits
Easy
Surrounded Regions6 Months
Medium
Search in a Binary Search Tree
Easy
Nested List Weight Sum
Medium
Largest Divisible Subset
Medium
Number of Valid Words in a Sentence
Easy
Element Appearing More Than 25% In Sorted Array
Easy
Least Number of Unique Integers after K Removals
Medium
Find in Mountain Array6 Months
Hard
Maximum Employees to Be Invited to a Meeting
Hard
Meeting Rooms6 Months
Easy
Closest Binary Search Tree Value
Easy
The kth Factor of n
Medium
Binary Tree Vertical Order Traversal
Medium
Minimum Cost to Cut a Stick
Hard