Top 100 Coding Interview Questions 2026 (FAANG-Tested)

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These are the 100 coding interview questions that FAANG and top-tier tech companies actually ask in 2026, grouped by topic with LeetCode links. Cover all 100 and you can walk into any coding interview loop with confidence. Cover the top 50 and you handle Manila enterprise, Toptal, and remote US junior developer roles. This list is the cornerstone reference of our Batch 11-C DSA cluster, linking back to all the tutorials that teach each pattern.

Top 100 Coding Interview Questions 2026 (FAANG-Tested)
Top 100 Coding Interview Questions 2026 (FAANG-Tested)

Quick 2026 verdict

Grinding these 100 problems (with understanding, not memorization) is the fastest path to interview-ready. Follow our DSA Roadmap for BSIT Students 2026 for the pacing, use this list for the actual problems, and study each pattern with the linked tutorials in this Batch 11-C cluster. Difficulty split: 25 Easy, 60 Medium, 15 Hard. Time to complete at 1-2 problems per day: 3-4 months.

Arrays and Hashing (15 problems)

  1. Two Sum (Easy), LeetCode 1. Learn the “value to index” hashmap pattern.
  2. Contains Duplicate (Easy), LeetCode 217. Set membership check.
  3. Valid Anagram (Easy), LeetCode 242. Counter comparison.
  4. Group Anagrams (Medium), LeetCode 49. defaultdict + sorted key.
  5. Top K Frequent Elements (Medium), LeetCode 347. Counter.most_common or bucket sort.
  6. Product of Array Except Self (Medium), LeetCode 238. Prefix / suffix products.
  7. Valid Sudoku (Medium), LeetCode 36. Set validation across rows, cols, boxes.
  8. Encode and Decode Strings (Medium), LeetCode 271. Length prefix delimiter.
  9. Longest Consecutive Sequence (Medium), LeetCode 128. Set + scan starts.
  10. Best Time to Buy and Sell Stock (Easy), LeetCode 121. Running min + max profit.
  11. Maximum Subarray (Medium), LeetCode 53. Kadane’s algorithm.
  12. Merge Intervals (Medium), LeetCode 56. Sort + sweep.
  13. Rotate Image (Medium), LeetCode 48. Transpose + reverse rows.
  14. Spiral Matrix (Medium), LeetCode 54. Boundary shrink pattern.
  15. Set Matrix Zeroes (Medium), LeetCode 73. In-place marking with first row/col.

Study pattern: HashMap Deep Dive Python + Java + JavaScript 2026

Two Pointers and Sliding Window (10 problems)

  1. Valid Palindrome (Easy), LeetCode 125.
  2. Two Sum II Input Array Is Sorted (Medium), LeetCode 167.
  3. 3Sum (Medium), LeetCode 15. Sort + two pointers.
  4. Container With Most Water (Medium), LeetCode 11.
  5. Trapping Rain Water (Hard), LeetCode 42. Two pointers OR precomputed max.
  6. Best Time to Buy and Sell Stock II (Medium), LeetCode 122.
  7. Longest Substring Without Repeating Characters (Medium), LeetCode 3.
  8. Longest Repeating Character Replacement (Medium), LeetCode 424.
  9. Permutation in String (Medium), LeetCode 567. Sliding window Counter compare.
  10. Minimum Window Substring (Hard), LeetCode 76. Textbook sliding window.

Stack (7 problems)

  1. Valid Parentheses (Easy), LeetCode 20.
  2. Min Stack (Medium), LeetCode 155. Auxiliary stack of min-so-far.
  3. Evaluate Reverse Polish Notation (Medium), LeetCode 150.
  4. Generate Parentheses (Medium), LeetCode 22. Backtracking.
  5. Daily Temperatures (Medium), LeetCode 739. Monotonic stack.
  6. Car Fleet (Medium), LeetCode 853.
  7. Largest Rectangle in Histogram (Hard), LeetCode 84. Monotonic stack.

Binary Search (7 problems)

  1. Binary Search (Easy), LeetCode 704.
  2. Search a 2D Matrix (Medium), LeetCode 74.
  3. Koko Eating Bananas (Medium), LeetCode 875. Binary search on answer.
  4. Find Minimum in Rotated Sorted Array (Medium), LeetCode 153.
  5. Search in Rotated Sorted Array (Medium), LeetCode 33.
  6. Time Based Key-Value Store (Medium), LeetCode 981.
  7. Median of Two Sorted Arrays (Hard), LeetCode 4.

Linked List (11 problems)

  1. Reverse Linked List (Easy), LeetCode 206.
  2. Merge Two Sorted Lists (Easy), LeetCode 21.
  3. Linked List Cycle (Easy), LeetCode 141. Floyd’s tortoise and hare.
  4. Reorder List (Medium), LeetCode 143.
  5. Remove Nth Node From End of List (Medium), LeetCode 19.
  6. Copy List With Random Pointer (Medium), LeetCode 138.
  7. Add Two Numbers (Medium), LeetCode 2.
  8. Find the Duplicate Number (Medium), LeetCode 287. Cycle detection.
  9. LRU Cache (Medium), LeetCode 146. Doubly linked list + hashmap.
  10. Merge K Sorted Lists (Hard), LeetCode 23. Heap-based.
  11. Reverse Nodes in K Group (Hard), LeetCode 25.

Trees (13 problems)

  1. Invert Binary Tree (Easy), LeetCode 226.
  2. Maximum Depth of Binary Tree (Easy), LeetCode 104.
  3. Diameter of Binary Tree (Easy), LeetCode 543.
  4. Balanced Binary Tree (Easy), LeetCode 110.
  5. Same Tree (Easy), LeetCode 100.
  6. Subtree of Another Tree (Easy), LeetCode 572.
  7. Lowest Common Ancestor of a BST (Medium), LeetCode 235.
  8. Binary Tree Level Order Traversal (Medium), LeetCode 102.
  9. Binary Tree Right Side View (Medium), LeetCode 199.
  10. Count Good Nodes in Binary Tree (Medium), LeetCode 1448.
  11. Validate Binary Search Tree (Medium), LeetCode 98.
  12. Kth Smallest Element in a BST (Medium), LeetCode 230.
  13. Serialize and Deserialize Binary Tree (Hard), LeetCode 297.

Study pattern: Binary Tree Complete Tutorial with Python 2026

Heap and Priority Queue (7 problems)

  1. Kth Largest Element in a Stream (Easy), LeetCode 703.
  2. Last Stone Weight (Easy), LeetCode 1046.
  3. K Closest Points to Origin (Medium), LeetCode 973.
  4. Kth Largest Element in Array (Medium), LeetCode 215.
  5. Task Scheduler (Medium), LeetCode 621.
  6. Design Twitter (Medium), LeetCode 355.
  7. Find Median From Data Stream (Hard), LeetCode 295. Two heaps.

Backtracking (9 problems)

  1. Subsets (Medium), LeetCode 78.
  2. Combination Sum (Medium), LeetCode 39.
  3. Permutations (Medium), LeetCode 46.
  4. Subsets II (Medium), LeetCode 90.
  5. Combination Sum II (Medium), LeetCode 40.
  6. Word Search (Medium), LeetCode 79. DFS with visited tracking.
  7. Palindrome Partitioning (Medium), LeetCode 131.
  8. Letter Combinations of a Phone Number (Medium), LeetCode 17.
  9. N-Queens (Hard), LeetCode 51.

Graphs (10 problems)

  1. Number of Islands (Medium), LeetCode 200. DFS or BFS.
  2. Clone Graph (Medium), LeetCode 133.
  3. Max Area of Island (Medium), LeetCode 695.
  4. Pacific Atlantic Water Flow (Medium), LeetCode 417.
  5. Surrounded Regions (Medium), LeetCode 130.
  6. Rotting Oranges (Medium), LeetCode 994. Multi-source BFS.
  7. Walls and Gates (Medium), LeetCode 286.
  8. Course Schedule (Medium), LeetCode 207. Topological sort.
  9. Course Schedule II (Medium), LeetCode 210.
  10. Redundant Connection (Medium), LeetCode 684. Union-Find.

Study pattern: Graph Algorithms Complete 2026 Guide

1D Dynamic Programming (7 problems)

  1. Climbing Stairs (Easy), LeetCode 70.
  2. Min Cost Climbing Stairs (Easy), LeetCode 746.
  3. House Robber (Medium), LeetCode 198.
  4. House Robber II (Medium), LeetCode 213.
  5. Longest Palindromic Substring (Medium), LeetCode 5.
  6. Palindromic Substrings (Medium), LeetCode 647.
  7. Decode Ways (Medium), LeetCode 91.

2D Dynamic Programming (4 problems)

  1. Unique Paths (Medium), LeetCode 62.
  2. Longest Common Subsequence (Medium), LeetCode 1143.
  3. Coin Change (Medium), LeetCode 322.
  4. Edit Distance (Medium), LeetCode 72.

Study pattern: Dynamic Programming Beginners Guide 2026

How to use this list

  • Follow the group order. Arrays first, then Two Pointers, then Stack. Do not jump to DP or Graphs before mastering foundations.
  • 1-2 problems per day. Not 10 per day. Depth beats volume.
  • Struggle 30 minutes before reading the editorial. Real learning happens during the struggle, not during the reading.
  • Come back to a problem 1 week later. If you can solve it fresh, you actually learned the pattern. If not, redo.
  • State the complexity out loud after each. Interview practice happens here.

Official documentation

Frequently Asked Questions

Are these the “actual” FAANG interview questions?

These are the patterns FAANG interviewers pull from. Specific problems rotate, but the underlying patterns (two pointers, sliding window, BFS/DFS, DP) do not. Master the 100 above and you can adapt to any specific variant an interviewer throws at you.

How long to complete all 100?

At 1-2 problems per day, about 3-4 months. Some problems (Hard DP, Merge K Sorted Lists) take multiple sessions. Give yourself 20 weeks for full coverage including review. Rushing to finish in 6 weeks yields shallow understanding and interview failure.

Do I need all 100 to pass interviews?

No. The first 50 (through Trees) cover 80 percent of Manila enterprise interviews (Accenture, IBM, Cognizant, PayMongo, Sprout). Problems 51-100 (DP, advanced Graphs, backtracking) push you to FAANG-level readiness. Cover the first 50 for junior roles, all 100 for FAANG.

What about Hard problems I cannot solve?

Hard problems (Trapping Rain Water, Median of Two Sorted Arrays, Word Ladder II) test edge cases most junior interviews do not reach. Attempt them, read the editorial, understand the pattern, move on. Do not spend 3 days stuck on one Hard when you could complete 5 Mediums in the same time.

What language should I solve them in?

Python for most PH BSIT students in 2026. Cleanest syntax, fastest to write, accepted by every serious tech interviewer. JavaScript is a close second if you are targeting frontend or full-stack roles. Java only if your target company explicitly requires it.

Should I do the LeetCode contests?

Yes, especially in month 3-4. Weekly and Biweekly contests train timed problem solving under pressure, which no amount of untimed practice replicates. Aim for 2-3 out of 4 problems in the 90-minute contest. Consistent contest rating over 1,800 signals FAANG readiness.

Related DSA + Interview tutorials (complete Batch 11-C)

  • DSA Roadmap for BSIT Students 2026
  • Big-O Notation Complete Guide for Beginners 2026
  • Recursion Explained with Real Examples 2026
  • Sorting Algorithms Cheat Sheet 2026
  • HashMap Deep Dive 2026 Python + Java + JavaScript
  • Binary Tree Complete Tutorial with Python 2026
  • Dynamic Programming Beginners Guide 2026
  • Graph Algorithms Complete 2026 Guide
  • LeetCode vs HackerRank vs Codewars 2026

Official platforms

Related tutorials

Adones Evangelista

Programmer & Technical Writer at PIES IT Solution

Adones Evangelista is a programmer and writer at PIES IT Solution, author of over 900 tutorials and error-fix guides at itsourcecode.com. Specializes in JavaScript, Django, Laravel, and Python error debugging covering ValueError, TypeError, AttributeError, ModuleNotFoundError, and RuntimeError, plus C/C++ and PHP capstone projects for BSIT students.

Expertise: JavaScript · Python · Django · Laravel · Error Debugging · C/C++  · View all posts by Adones Evangelista →

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