Oracle coding interview
questions, leaked.
163 problems reported across recent Oracle interviews. Top patterns: array, string, hash table. The list below is what most candidates actually saw, plus the honest play if you can't grind all of it.
Oracle's assessment is array and string heavy, with 79 array problems out of 163 total. You're walking into a Medium-dominated gauntlet: 96 of those 163 are Medium difficulty, and the top problems span sliding windows, hash tables, and two-pointer patterns that eat up interview time. You need to be fast on Two Sum and Merge Intervals, sharp on LRU Cache and Longest Substring Without Repeating Characters, and ready for the curveball hard problems like Merge k Sorted Lists. If you blank mid-assessment, StealthCoder solves it invisibly while you stay on camera.
Top problems at Oracle
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | LRU Cache | MEDIUM | 100.0 | 45% | Hash Table · Linked List · Design |
| 02 | Find Median from Data Stream | HARD | 0.0 | 53% | Two Pointers · Design · Sorting |
| 03 | Number of Islands | MEDIUM | 89.5 | 62% | Array · Depth-First Search · Breadth-First Search |
| 04 | Two Sum | EASY | 88.3 | 56% | Array · Hash Table |
| 05 | Longest Substring Without Repeating Characters | MEDIUM | 85.8 | 37% | Hash Table · String · Sliding Window |
| 06 | Merge Intervals | MEDIUM | 85.1 | 49% | Array · Sorting |
| 07 | Group Anagrams | MEDIUM | 82.2 | 71% | Array · Hash Table · String |
| 08 | Koko Eating Bananas | MEDIUM | 0.0 | 49% | Array · Binary Search |
| 09 | Permutation in String | MEDIUM | 0.0 | 47% | Hash Table · Two Pointers · String |
| 10 | Simplify Path | MEDIUM | 0.0 | 48% | String · Stack |
| 11 | Longest Palindromic Substring | MEDIUM | 77.8 | 36% | Two Pointers · String · Dynamic Programming |
| 12 | Merge k Sorted Lists | HARD | 72.5 | 57% | Linked List · Divide and Conquer · Heap (Priority Queue) |
| 13 | Container With Most Water | MEDIUM | 71.2 | 58% | Array · Two Pointers · Greedy |
| 14 | Sliding Window Maximum | HARD | 71.2 | 48% | Array · Queue · Sliding Window |
| 15 | Search in Rotated Sorted Array | MEDIUM | 71.2 | 43% | Array · Binary Search |
| 16 | Binary Tree Right Side View | MEDIUM | 69.9 | 67% | Tree · Depth-First Search · Breadth-First Search |
| 17 | Longest Consecutive Sequence | MEDIUM | 68.5 | 47% | Array · Hash Table · Union Find |
| 18 | Spiral Matrix | MEDIUM | 66.9 | 54% | Array · Matrix · Simulation |
| 19 | Add Two Numbers | MEDIUM | 66.9 | 46% | Linked List · Math · Recursion |
| 20 | Trapping Rain Water | HARD | 66.9 | 65% | Array · Two Pointers · Dynamic Programming |
| 21 | Reverse Linked List | EASY | 63.6 | 79% | Linked List · Recursion |
| 22 | Best Time to Buy and Sell Stock | EASY | 61.6 | 55% | Array · Dynamic Programming |
| 23 | 3Sum | MEDIUM | 61.6 | 37% | Array · Two Pointers · Sorting |
| 24 | Jump Game | MEDIUM | 61.6 | 39% | Array · Dynamic Programming · Greedy |
| 25 | Roman to Integer | EASY | 61.6 | 65% | Hash Table · Math · String |
| 26 | Course Schedule | MEDIUM | 61.6 | 49% | Depth-First Search · Breadth-First Search · Graph |
| 27 | Pow(x, n) | MEDIUM | 61.6 | 37% | Math · Recursion |
| 28 | Merge Two Sorted Lists | EASY | 61.6 | 67% | Linked List · Recursion |
| 29 | Binary Tree Zigzag Level Order Traversal | MEDIUM | 59.6 | 62% | Tree · Breadth-First Search · Binary Tree |
| 30 | Gas Station | MEDIUM | 59.6 | 46% | Array · Greedy |
| 31 | Binary Tree Maximum Path Sum | HARD | 59.6 | 41% | Dynamic Programming · Tree · Depth-First Search |
| 32 | Course Schedule II | MEDIUM | 59.6 | 53% | Depth-First Search · Breadth-First Search · Graph |
| 33 | Search a 2D Matrix II | MEDIUM | 59.6 | 55% | Array · Binary Search · Divide and Conquer |
| 34 | First Missing Positive | HARD | 57.3 | 41% | Array · Hash Table |
| 35 | Longest Common Prefix | EASY | 57.3 | 45% | String · Trie |
| 36 | Word Search | MEDIUM | 57.3 | 45% | Array · String · Backtracking |
| 37 | Maximum Subarray | MEDIUM | 57.3 | 52% | Array · Divide and Conquer · Dynamic Programming |
| 38 | Restore IP Addresses | MEDIUM | 54.7 | 53% | String · Backtracking |
| 39 | Validate Binary Search Tree | MEDIUM | 54.7 | 34% | Tree · Depth-First Search · Binary Search Tree |
| 40 | Kth Largest Element in an Array | MEDIUM | 54.7 | 68% | Array · Divide and Conquer · Sorting |
| 41 | Min Stack | MEDIUM | 54.7 | 56% | Stack · Design |
| 42 | Product of Array Except Self | MEDIUM | 54.7 | 68% | Array · Prefix Sum |
| 43 | Combination Sum | MEDIUM | 54.7 | 75% | Array · Backtracking |
| 44 | Linked List Cycle | EASY | 54.7 | 53% | Hash Table · Linked List · Two Pointers |
| 45 | Set Matrix Zeroes | MEDIUM | 54.7 | 61% | Array · Hash Table · Matrix |
| 46 | Lowest Common Ancestor of a Binary Tree | MEDIUM | 54.7 | 67% | Tree · Depth-First Search · Binary Tree |
| 47 | Sort Colors | MEDIUM | 51.8 | 68% | Array · Two Pointers · Sorting |
| 48 | Zigzag Conversion | MEDIUM | 51.8 | 52% | String |
| 49 | Valid Anagram | EASY | 51.8 | 67% | Hash Table · String · Sorting |
| 50 | Maximal Square | MEDIUM | 51.8 | 49% | Array · Dynamic Programming · Matrix |
Frequencies derived from public community-tagged interview reports. Click a row to view on LeetCode.
You have a week, maybe less. You can't out-grind the list above. StealthCoder runs invisibly during the actual Oracle OA. The proctor cannot see it. Screen share cannot detect it. Built by an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage.
Get StealthCoder- array79 · 48%
- string47 · 29%
- hash table41 · 25%
- dynamic programming25 · 15%
- two pointers23 · 14%
- sorting21 · 13%
- binary search20 · 12%
- math19 · 12%
- linked list18 · 11%
- stack17 · 10%
Arrays dominate the distribution, followed by strings and hash tables. This tells you Oracle cares about sequence manipulation and indexing speed. Two-pointers and binary search are survival skills here, not nice-to-haves. You'll see sliding window problems (Longest Substring, Permutation in String, Sliding Window Maximum) that trip up candidates who haven't drilled the pattern. Dynamic programming sits at 25 problems, low enough that you shouldn't obsess over it first, but high enough to cost you if you skip it. The hard tier (Merge k Sorted Lists, Sliding Window Maximum, Find Median from Data Stream) leans on heap and design, so mock those under timer pressure. When you hit the live OA, StealthCoder is your safety net for the design problems and heap logic that you didn't have time to memorize.
Companies with similar patterns
If you prepped for Oracle, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Oracle.
Memorizing every problem above in a week is a fantasy. StealthCoder is the hedge: an AI overlay that's invisible during screen share. It reads the problem on screen and surfaces a working solution in under 2 seconds. Built by an engineer who got tired of watching his cohort grind for six months and still get filtered at the OA stage. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Oracle interview FAQ
Should I drill arrays first for Oracle?+
Yes. Arrays account for 79 of 163 problems. Start with Two Sum and Merge Intervals, then move to Koko Eating Bananas and Container With Most Water. You'll see array patterns in 8 of the top 15 problems. Hash table and string problems often layer on top of array traversal, so master indexing and bounds first.
How much time should I spend on dynamic programming?+
25 problems out of 163 is meaningful but not the priority. Drill arrays, strings, and hash tables first. Hit DP after you're solid on sliding windows and two-pointers. Longest Palindromic Substring is the DP overlap you'll see, but it's also solvable with two-pointers, so don't over-prepare here.
Is LRU Cache worth the effort?+
Yes. It's the signature hard problem in Oracle reports and combines hash table, linked list, and design. Spend a full session on it. Understand the doubly-linked-list mechanics and the O(1) get/put logic. This problem separates candidates who think algorithmically from those who memorize solutions.
What's the gap between Medium and Hard here?+
Hard problems (26 total) flip the script to heaps, design, and complex traversals. Merge k Sorted Lists and Sliding Window Maximum require data-structure knowledge that Medium problems don't test. If you pass all Mediums, don't assume you're ready for Hard. Mock them separately under timer pressure.
Should I study two-pointers before binary search?+
Two-pointers first. It appears in 23 problems and shows up in 6 of the top 15 (Merge Intervals, Container With Most Water, Permutation in String, Longest Palindromic Substring, Find Median, Merge k Sorted Lists). Binary search is another 20 problems, but two-pointer patterns recur faster in the live assessment.