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Microsoft — DSA Questions

553 problems confirmed in interviews | 1509 total tagged

Problem titles link to LeetCode. Interview mention counts are derived from our analysis of public discussion posts.

Priority List (confirmed in interviews)

# Problem Difficulty Tags Seen LC Editorial Video
1 LRU Cache Medium HashMap / Design 15x LC
2 Number of Islands Medium Graph 14x LC
3 Meeting Rooms II Medium Intervals 12x LC
4 Search in Rotated Sorted Array Medium Binary Search 11x LC
5 Course Schedule II Medium Graph 11x LC
6 Valid Parentheses Easy Stack / Queue 10x LC
7 Longest Substring Without Repeating Characters Medium Tree 9x LC
8 Best Time to Buy and Sell Stock Easy Other 9x LC
9 Two Sum Easy Array / Two Pointers 8x LC
10 Container With Most Water Medium Array / Two Pointers 8x LC
11 3Sum Medium Array, Two Pointers, Sorting 8x LC
12 Group Anagrams Medium Array, Hash Table, String 8x LC
13 Binary Tree Zigzag Level Order Traversal Medium Tree 8x LC
14 Construct Binary Tree from Preorder and Inorder Travers Medium Tree 8x LC
15 Reverse Words in a String Medium Two Pointers, String 8x LC
16 Lowest Common Ancestor of a Binary Tree Medium Tree 8x LC
17 Merge k Sorted Lists Hard Heap / PQ 7x LC
18 Trapping Rain Water Hard Array / Two Pointers 7x LC
19 Spiral Matrix Medium Matrix / Grid 7x LC
20 Jump Game Medium DP 7x LC
21 Merge Intervals Medium Array, Sorting 7x LC
22 Word Ladder Hard Other 7x LC
23 Reverse Linked List Easy Linked List 7x LC
24 Course Schedule Medium Graph 7x LC
25 Rotting Oranges Medium Graph 7x LC
26 Redundant Connection Medium Other 7x LC
27 Add Two Numbers Medium Linked List 6x LC
28 Generate Parentheses Medium String, Dynamic Programming, Backtracking 6x LC
29 Reverse Nodes in k-Group Hard Other 6x LC
30 Decode Ways Medium DP 6x LC
31 Validate Binary Search Tree Medium Tree, Depth-First Search, Binary Search Tree 6x LC
32 Binary Tree Level Order Traversal Medium Tree 6x LC
33 Longest Consecutive Sequence Medium Array, Hash Table, Union-Find 6x LC
34 Gas Station Medium Array, Greedy 6x LC
35 Critical Connections in a Network Hard Graph 6x LC
36 Median of Two Sorted Arrays Hard Other 5x LC
37 Jump Game II Medium DP 5x LC
38 Maximum Subarray Medium Array / Two Pointers 5x LC
39 Climbing Stairs Easy DP 5x LC
40 Sort Colors Medium Array, Two Pointers, Sorting 5x LC
41 Minimum Window Substring Hard Tree 5x LC
42 Word Search Medium Backtracking 5x LC
43 Binary Tree Maximum Path Sum Hard Tree 5x LC
44 Copy List with Random Pointer Medium Hash Table, Linked List 5x LC
45 Word Break Medium DP 5x LC
46 Kth Largest Element in an Array Medium Heap / PQ 5x LC
47 Kth Smallest Element in a BST Medium Tree 5x LC
48 Product of Array Except Self Medium Array / Two Pointers 5x LC
49 Find the Duplicate Number Medium Array, Two Pointers, Binary Search 5x LC
50 Serialize and Deserialize Binary Tree Hard String, Tree, Depth-First Search 5x LC
51 Diameter of Binary Tree Easy Tree 5x LC
52 Network Delay Time Medium Depth-First Search, Breadth-First Search, Graph Theory 5x LC
53 Reorganize String Medium Heap / PQ 5x LC
54 Cheapest Flights Within K Stops Medium Graph 5x LC
55 Pacific Atlantic Water Flow Medium Other 5x LC
56 Longest Palindromic Substring Medium Tree 4x LC
57 Remove Duplicates from Sorted Array Easy Array / Two Pointers 4x LC
58 Find First and Last Position of Element in Sorted Array Medium Binary Search 4x LC
59 Combination Sum Medium Backtracking 4x LC
60 Largest Rectangle in Histogram Hard Stack / Queue 4x LC
61 Maximal Rectangle Hard Array, Dynamic Programming, Stack 4x LC
62 Populating Next Right Pointers in Each Node Medium Linked List, Tree, Depth-First Search 4x LC
63 Min Stack Medium Stack / Queue 4x LC
64 Intersection of Two Linked Lists Easy Linked List 4x LC
65 Binary Tree Right Side View Medium Tree 4x LC
66 Implement Trie (Prefix Tree) Medium Tree 4x LC
67 Basic Calculator II Medium Stack / Queue 4x LC
68 Sliding Window Maximum Hard Array, Queue, Sliding Window 4x LC
69 Alien Dictionary Hard Graph 4x LC
70 Longest Increasing Subsequence Medium DP 4x LC
71 Coin Change Medium DP 4x LC
72 Kth Smallest Element in a Sorted Matrix Medium Matrix / Grid 4x LC
73 Partition Equal Subset Sum Medium Backtracking 4x LC
74 Next Greater Element II Medium Other 4x LC
75 Subarray Sum Equals K Medium Array / Two Pointers 4x LC
76 Task Scheduler Medium Heap / PQ 4x LC
77 Max Area of Island Medium Graph 4x LC
78 Car Fleet Medium Other 4x LC
79 Binary Tree Cameras Hard Tree 4x LC
80 Longest Happy String Medium Other 4x LC

Graph (47 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Number of Islands Medium 14x LC
2 Course Schedule II Medium 11x LC
3 Course Schedule Medium 7x LC
4 Rotting Oranges Medium 7x LC
5 Critical Connections in a Network Hard 6x LC
6 Network Delay Time Medium Depth-First Search, Breadth-First Search, Graph Theory 5x LC
7 Cheapest Flights Within K Stops Medium 5x LC
8 Alien Dictionary Hard 4x LC
9 Max Area of Island Medium 4x LC
10 Bus Routes Hard 4x LC
11 Graph Valid Tree Medium Depth-First Search, Breadth-First Search, Union-Find 3x LC
12 Reconstruct Itinerary Hard Array, String, Depth-First Search 3x LC
13 Is Graph Bipartite? Medium Depth-First Search, Breadth-First Search, Union-Find 2x LC
14 Maximal Network Rank Medium 2x LC
15 Maximum Subgraph Score in a Tree Hard Array, Dynamic Programming, Tree 2x LC
16 Lexicographically Smallest Negated Permutation That Sum ? 2x LC
17 Lexicographically Smallest Palindromic Permutation Grea ? 2x LC
18 Lexicographically Smallest Permutation Greater Than Tar Medium Hash Table, String, Greedy 2x LC
19 Clone Graph Medium 1x LC
20 Evaluate Division Medium 1x LC
21 Reorder Routes to Make All Paths Lead to the City Zero Medium 1x LC
22 Number of Operations to Make Network Connected Medium 1x LC
23 Count Unreachable Pairs of Nodes in an Undirected Graph Medium 1x LC
24 Count Routes to Climb a Rectangular Grid Hard 1x LC
25 Shortest Cycle in a Graph Hard Breadth-First Search, Graph Theory 1x LC
26 Lexicographically Smallest String After Deleting Duplic ? 1x LC
27 Largest Color Value In A Directed Graph ? 1x LC
28 Number Of Connected Components In An Undirected Graph ? 1x LC
29 Lexicographically Smallest Equivalent String ? 1x LC
30 Island Perimeter Easy LC
31 Number of Distinct Islands Medium LC
32 Verifying an Alien Dictionary Easy LC
33 Number of Closed Islands Medium LC
34 The k-th Lexicographical String of All Happy Strings of Medium String, Backtracking LC
35 Find Center of Star Graph Easy LC
36 Find if Path Exists in Graph Easy Depth-First Search, Breadth-First Search, Union-Find LC
37 Making A Large Island Hard LC
38 Lexicographical Numbers Medium LC
39 K-th Smallest in Lexicographical Order Hard LC
40 Course Schedule IV Medium LC
41 Construct the Lexicographically Largest Valid Sequence Medium LC
42 Minimum Cost Walk in Weighted Graph Hard LC
43 Find the Lexicographically Largest String From the Box Medium Two Pointers, String, Enumeration LC
44 Lexicographically Minimum String After Removing Stars Medium Hash Table, String, Stack LC
45 Last Substring in Lexicographical Order Hard Two Pointers, String LC
46 Implement Router Medium LC
47 Distance to a Cycle in Undirected Graph Hard LC

DP (31 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Jump Game Medium 7x LC
2 Decode Ways Medium 6x LC
3 Jump Game II Medium 5x LC
4 Climbing Stairs Easy 5x LC
5 Word Break Medium 5x LC
6 Longest Increasing Subsequence Medium 4x LC
7 Coin Change Medium 4x LC
8 Regular Expression Matching Hard String, Dynamic Programming, Recursion 3x LC
9 Maximum Profit in Job Scheduling Hard 3x LC
10 Wildcard Matching Hard 2x LC
11 Unique Paths Medium 2x LC
12 Minimum Path Sum Medium 2x LC
13 Edit Distance Medium 2x LC
14 House Robber Medium 2x LC
15 Longest Increasing Path in a Matrix Hard 2x LC
16 House Robber III Medium Dynamic Programming, Tree, Depth-First Search 2x LC
17 Total Score Of Dungeon Runs ? 2x LC
18 Unique Paths II Medium 1x LC
19 Jump Game III Medium 1x LC
20 Cherry Pickup II Hard 1x LC
21 Minimum Path Cost In A Grid ? 1x LC
22 Word Break II Hard Array, Hash Table, String LC
23 Dungeon Game Hard LC
24 House Robber II Medium LC
25 Coin Change II Medium LC
26 Cherry Pickup Hard LC
27 Min Cost Climbing Stairs Easy LC
28 Number of Longest Increasing Subsequence Medium LC
29 House Robber IV Medium LC
30 Jump Game VI Medium LC
31 Unique Paths III Hard LC

Tree (154 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Longest Substring Without Repeating Characters Medium 9x LC
2 Binary Tree Zigzag Level Order Traversal Medium 8x LC
3 Construct Binary Tree from Preorder and Inorder Travers Medium 8x LC
4 Lowest Common Ancestor of a Binary Tree Medium 8x LC
5 Validate Binary Search Tree Medium Tree, Depth-First Search, Binary Search Tree 6x LC
6 Binary Tree Level Order Traversal Medium 6x LC
7 Minimum Window Substring Hard 5x LC
8 Binary Tree Maximum Path Sum Hard 5x LC
9 Kth Smallest Element in a BST Medium 5x LC
10 Serialize and Deserialize Binary Tree Hard String, Tree, Depth-First Search 5x LC
11 Diameter of Binary Tree Easy 5x LC
12 Longest Palindromic Substring Medium 4x LC
13 Binary Tree Right Side View Medium 4x LC
14 Implement Trie (Prefix Tree) Medium 4x LC
15 Binary Tree Cameras Hard 4x LC
16 Count Good Nodes in Binary Tree Medium 4x LC
17 Recover Binary Search Tree Medium 3x LC
18 Flatten Binary Tree to Linked List Medium Linked List, Stack, Tree 3x LC
19 Binary Search Tree Iterator Medium 3x LC
20 Invert Binary Tree Easy Tree, Depth-First Search, Breadth-First Search 3x LC
21 Lowest Common Ancestor of a Binary Search Tree Medium 3x LC
22 All Nodes Distance K in Binary Tree Medium 3x LC
23 N-ary Tree Level Order Traversal Medium 3x LC
24 Unique Binary Search Trees Medium 2x LC
25 Same Tree Easy 2x LC
26 Symmetric Tree Easy 2x LC
27 Maximum Depth of Binary Tree Easy 2x LC
28 Convert Sorted Array to Binary Search Tree Easy 2x LC
29 Convert Sorted List to Binary Search Tree Medium 2x LC
30 Count Complete Tree Nodes Easy 2x LC
31 Minimum Height Trees Medium 2x LC
32 Longest Substring with At Most K Distinct Characters Medium Hash Table, String, Sliding Window 2x LC
33 Delete Node in a BST Medium Tree, Binary Search Tree, Binary Tree 2x LC
34 Subtree of Another Tree Easy 2x LC
35 Palindromic Substrings Medium 2x LC
36 Two Sum IV - Input is a BST Easy 2x LC
37 Distribute Coins in Binary Tree Medium 2x LC
38 Vertical Order Traversal of a Binary Tree Hard 2x LC
39 Cousins in Binary Tree Easy 2x LC
40 Longest Balanced Substring II Medium 2x LC
41 Total Sum Of Interaction Cost In Tree Groups ? 2x LC
42 Minimum Deletions To Make Alternating Substring ? 2x LC
43 Remove K Balanced Substrings ? 2x LC
44 Distinct Points Reachable After Substring Removal ? 2x LC
45 Substring with Concatenation of All Words Hard 1x LC
46 Binary Tree Inorder Traversal Easy Stack, Tree, Depth-First Search 1x LC
47 Unique Binary Search Trees II Medium 1x LC
48 Construct Binary Tree from Inorder and Postorder Traver Medium 1x LC
49 Balanced Binary Tree Easy Tree, Depth-First Search, Binary Tree 1x LC
50 Minimum Depth of Binary Tree Easy Tree, Depth-First Search, Breadth-First Search 1x LC

...and 104 more in this category.

Array / Two Pointers (79 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Two Sum Easy 8x LC
2 Container With Most Water Medium 8x LC
3 Trapping Rain Water Hard 7x LC
4 Maximum Subarray Medium 5x LC
5 Product of Array Except Self Medium 5x LC
6 Remove Duplicates from Sorted Array Easy 4x LC
7 Subarray Sum Equals K Medium 4x LC
8 Remove Duplicates from Sorted List Easy 3x LC
9 Maximum Product Subarray Medium Array, Dynamic Programming 3x LC
10 Merge Sorted Array Easy 2x LC
11 Longest Continuous Subarray With Absolute Diff Less Tha Medium 2x LC
12 Stable Subarrays With Equal Boundary and Interior Sum Medium 2x LC
13 Minimum Inversion Count In Subarrays Of Fixed Length ? 2x LC
14 Minimum Operations To Equalize Subarrays ? 2x LC
15 Count Stable Subarrays ? 2x LC
16 Longest Non Decreasing Subarray After Replacing At Most ? 2x LC
17 Count Subarrays With Majority Element Ii ? 2x LC
18 Count Distinct Subarrays Divisible By K In Sorted Array ? 2x LC
19 Longest Balanced Subarray II Hard Array, Hash Table, Divide and Conquer 2x LC
20 Maximum Total Subarray Value II Hard Array, Greedy, Segment Tree 2x LC
21 Count Bowl Subarrays Medium Array, Stack, Monotonic Stack 2x LC
22 Sum of Subarray Minimums Medium 1x LC
23 Subarrays with K Different Integers Hard 1x LC
24 Remove Duplicates From an Unsorted Linked List Medium 1x LC
25 Sum of Subarray Ranges Medium 1x LC
26 Count Subarrays With Fixed Bounds Hard 1x LC
27 Longest Alternating Subarray After Removing At Most One ? 1x LC
28 Minimum Cost to Merge Sorted Lists Hard Array, Two Pointers, Binary Search 1x LC
29 Maximum Subarray Min Product ? 1x LC
30 Maximum Sum Of Two Non Overlapping Subarrays ? 1x LC
31 Remove Duplicates from Sorted Array II Medium LC
32 Remove Duplicates from Sorted List II Medium LC
33 Two Sum II - Input Array Is Sorted Medium LC
34 Minimum Size Subarray Sum Medium LC
35 Maximum Size Subarray Sum Equals k Medium LC
36 Trapping Rain Water II Hard Array, Breadth-First Search, Heap (Priority Queue) LC
37 Continuous Subarray Sum Medium LC
38 Shortest Unsorted Continuous Subarray Medium LC
39 Maximum Average Subarray I Easy LC
40 Maximum Length of Repeated Subarray Medium Array, Binary Search, Dynamic Programming LC
41 Shortest Subarray with Sum at Least K Hard LC
42 Maximum Sum Circular Subarray Medium LC
43 Binary Subarrays With Sum Medium Array, Hash Table, Sliding Window LC
44 Subarray Sums Divisible by K Medium LC
45 Count Number of Nice Subarrays Medium LC
46 Maximum Sum of Distinct Subarrays With Length K Medium LC
47 Count Subarrays Where Max Element Appears at Least K Ti Medium LC
48 Longest Nice Subarray Medium LC
49 Make Two Arrays Equal by Reversing Subarrays Easy LC
50 Longest Turbulent Subarray Medium LC

...and 29 more in this category.

Sliding Window (4 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Sliding Window Maximum Hard Array, Queue, Sliding Window 4x LC
2 Longest Repeating Character Replacement Medium 2x LC
3 Sliding Window Median Hard 2x LC
4 Minimum Window Subsequence ? 1x LC

Intervals (13 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Meeting Rooms II Medium 12x LC
2 Merge Intervals Medium Array, Sorting 7x LC
3 Insert Interval Medium 3x LC
4 Non-overlapping Intervals Medium 3x LC
5 Count Integers in Intervals Hard Design, Segment Tree, Ordered Set 1x LC
6 Meeting Rooms Easy Array, Sorting LC
7 Count Odd Numbers in an Interval Range Easy LC
8 Partition Array into Disjoint Intervals Medium Array LC
9 Find Right Interval Medium LC
10 Interval List Intersections Medium Array, Two Pointers, Sweep Line LC
11 Divide Intervals Into Minimum Number of Groups Medium LC
12 Meeting Rooms III Hard LC
13 My Calendar I Medium LC

Heap / PQ (8 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Merge k Sorted Lists Hard 7x LC
2 Kth Largest Element in an Array Medium 5x LC
3 Reorganize String Medium 5x LC
4 Task Scheduler Medium 4x LC
5 Find Median from Data Stream Hard 3x LC
6 Top K Frequent Elements Medium 2x LC
7 Kth Largest Element in a Stream Easy 1x LC
8 Top K Frequent Words Medium LC

Stack / Queue (29 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Valid Parentheses Easy 10x LC
2 Generate Parentheses Medium String, Dynamic Programming, Backtracking 6x LC
3 Largest Rectangle in Histogram Hard 4x LC
4 Min Stack Medium 4x LC
5 Basic Calculator II Medium 4x LC
6 Daily Temperatures Medium Array, Stack, Monotonic Stack 3x LC
7 Minimum Remove to Make Valid Parentheses Medium String, Stack 3x LC
8 Implement Queue using Stacks Easy 2x LC
9 Maximum Frequency Stack Hard 2x LC
10 Remove Invalid Parentheses Hard String, Backtracking, Breadth-First Search 2x LC
11 Longest Valid Parentheses Hard String, Dynamic Programming, Stack 1x LC
12 Basic Calculator Hard 1x LC
13 Implement Stack using Queues Easy 1x LC
14 Valid Parenthesis String Medium 1x LC
15 Validate Stack Sequences Medium 1x LC
16 Minimum Insertions To Balance A Parentheses String ? 1x LC
17 Delete Middle Element Of A Stack ? 1x LC
18 Score Of Parentheses ? 1x LC
19 Max Stack ? 1x LC
20 Asteroid Collision Medium LC
21 Basic Calculator III Hard LC
22 Minimum Add to Make Parentheses Valid Medium LC
23 Remove Outermost Parentheses Easy LC
24 Different Ways to Add Parentheses Medium LC
25 Design a Stack With Increment Operation Medium LC
26 Maximum Nesting Depth of the Parentheses Easy LC
27 Broken Calculator Medium LC
28 Build an Array With Stack Operations Medium LC
29 Calculator with Method Chaining Easy LC

HashMap / Design (9 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 LRU Cache Medium 15x LC
2 Group Anagrams Medium Array, Hash Table, String 8x LC
3 Design Hit Counter Medium 2x LC
4 Insert Delete GetRandom O(1) Medium 2x LC
5 LFU Cache Hard 1x LC
6 First Unique Number Medium 1x LC
7 First Unique Character in a String Easy LC
8 Design HashMap Easy LC
9 Insert Delete GetRandom O(1) - Duplicates allowed Hard LC

Binary Search (7 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Search in Rotated Sorted Array Medium 11x LC
2 Find First and Last Position of Element in Sorted Array Medium 4x LC
3 Sqrt(x) Easy Math, Binary Search 1x LC
4 Search in Rotated Sorted Array II Medium Array, Binary Search 1x LC
5 Split Array Largest Sum Hard 1x LC
6 Binary Search Easy Array, Binary Search 1x LC
7 Binary Searchable Numbers in an Unsorted Array Medium 1x LC

String (34 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 String to Integer (atoi) Medium 3x LC
2 Valid Palindrome Easy 3x LC
3 Shortest Palindrome Hard 3x LC
4 Text Justification Hard Array, String, Simulation 2x LC
5 Count Binary Palindromic Numbers Hard Math, Bit Manipulation 2x LC
6 Palindrome Linked List Easy 1x LC
7 Valid Anagram Easy 1x LC
8 Find All Anagrams in a String Medium 1x LC
9 Palindrome Partitioning II Hard String, Dynamic Programming 1x LC
10 Count Palindromic Subsequences Hard 1x LC
11 Longest Palindromic Subsequence Medium String, Dynamic Programming 1x LC
12 Palindrome Partitioning Iii ? 1x LC
13 Count Different Palindromic Subsequences Hard String, Dynamic Programming 1x LC
14 Longest Chunked Palindrome Decomposition ? 1x LC
15 Palindrome Number Easy LC
16 Palindrome Partitioning Medium String, Dynamic Programming, Backtracking LC
17 Palindrome Permutation Easy LC
18 Encode and Decode Strings Medium Array, String, Design LC
19 Decode String Medium LC
20 Longest Palindrome Easy Hash Table, String, Greedy LC
21 Find the Closest Palindrome Hard Math, String LC
22 Valid Palindrome II Easy Two Pointers, String, Greedy LC
23 Palindrome Removal Hard LC
24 Minimum Number of Moves to Make Palindrome Hard Two Pointers, String, Greedy LC
25 Largest Palindromic Number Medium LC
26 Super Palindromes Hard LC
27 Unique Length-3 Palindromic Subsequences Medium LC
28 Construct K Palindrome Strings Medium LC
29 Smallest Palindromic Rearrangement I Medium LC
30 Longest Palindrome by Concatenating Two Letter Words Medium LC
31 Find Resultant Array After Removing Anagrams Easy LC
32 Minimum Number of Steps to Make Two Strings Anagram Medium LC
33 Maximum Palindromes After Operations Medium LC
34 Palindrome Pairs Hard LC

Backtracking (29 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Word Search Medium 5x LC
2 Combination Sum Medium 4x LC
3 Partition Equal Subset Sum Medium 4x LC
4 Letter Combinations of a Phone Number Medium Hash Table, String, Backtracking 3x LC
5 Next Permutation Medium Array, Two Pointers 3x LC
6 Word Search II Hard Array, String, Backtracking 3x LC
7 Sudoku Solver Hard 2x LC
8 Subsets Medium Array, Backtracking, Bit Manipulation 2x LC
9 Permutations Medium 1x LC
10 Combinations Medium 1x LC
11 Largest Divisible Subset Medium 1x LC
12 Combination Sum Iv ? 1x LC
13 Valid Sudoku Medium LC
14 Combination Sum II Medium LC
15 Permutations II Medium Array, Backtracking, Sorting LC
16 N-Queens Hard Array, Backtracking LC
17 N-Queens II Hard LC
18 Subsets II Medium LC
19 Permutation in String Medium LC
20 Partition to K Equal Sum Subsets Medium LC
21 Letter Case Permutation Medium LC
22 Previous Permutation With One Swap Medium LC
23 Largest Combination With Bitwise AND Greater Than Zero Medium LC
24 Count Number of Maximum Bitwise-OR Subsets Medium LC
25 Permutation Sequence Hard LC
26 Word Subsets Medium LC
27 Sum of All Subset XOR Totals Easy LC
28 Build Array from Permutation Easy Array, Simulation LC
29 Combination Sum III Medium LC

Matrix / Grid (22 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Spiral Matrix Medium 7x LC
2 Kth Smallest Element in a Sorted Matrix Medium 4x LC
3 Rotate Image Medium 3x LC
4 Set Matrix Zeroes Medium 3x LC
5 Spiral Matrix II Medium 1x LC
6 Search a 2D Matrix II Medium Array, Binary Search, Divide and Conquer 1x LC
7 Game of Life Medium 1x LC
8 01 Matrix Medium 1x LC
9 Transpose Matrix Easy Array, Matrix, Simulation 1x LC
10 Shortest Path in Binary Matrix Medium 1x LC
11 Minimum Cost Matrix Multiplication ? 1x LC
12 Search a 2D Matrix Medium LC
13 Spiral Matrix III Medium Array, Matrix, Simulation LC
14 Spiral Matrix IV Medium LC
15 Cells with Odd Values in a Matrix Easy LC
16 Maximum Matrix Sum Medium LC
17 Count Negative Numbers in a Sorted Matrix Easy LC
18 Determine Whether Matrix Can Be Obtained By Rotation Easy Array, Matrix LC
19 Matrix Diagonal Sum Easy LC
20 The K Weakest Rows in a Matrix Easy LC
21 Sort Matrix by Diagonals Medium LC
22 Paths in Matrix Whose Sum Is Divisible by K Hard LC

Linked List (29 problems)

# Problem Difficulty Tags Seen LC Editorial Video
1 Reverse Linked List Easy 7x LC
2 Add Two Numbers Medium 6x LC
3 Intersection of Two Linked Lists Easy 4x LC
4 Merge Two Sorted Lists Easy 3x LC
5 Linked List Cycle Easy Hash Table, Linked List, Two Pointers 3x LC
6 Add Two Numbers II Medium 3x LC
7 Linked List Cycle II Medium 2x LC
8 Swap Nodes in Pairs Medium 1x LC
9 Remove Linked List Elements Easy 1x LC
10 Middle of the Linked List Easy 1x LC
11 Flatten a Multilevel Doubly Linked List Medium 1x LC
12 Plus One Linked List Medium Linked List, Math 1x LC
13 Reverse Linked List II Medium LC
14 Delete Node in a Linked List Medium LC
15 Odd Even Linked List Medium LC
16 Design Linked List Medium LC
17 Next Greater Node In Linked List Medium LC
18 Convert Binary Number in a Linked List to Integer Easy LC
19 Delete N Nodes After M Nodes of a Linked List Easy LC
20 Merge In Between Linked Lists Medium LC
21 Delete the Middle Node of a Linked List Medium LC
22 Maximum Twin Sum of a Linked List Medium LC
23 Double a Number Represented as a Linked List Medium LC
24 Split Linked List in Parts Medium LC
25 Insert Greatest Common Divisors in Linked List Medium Linked List, Math, Number Theory LC
26 Remove Zero Sum Consecutive Nodes from Linked List Medium LC
27 Delete Nodes From Linked List Present in Array Medium Array, Hash Table, Linked List LC
28 Remove Nodes From Linked List Medium LC
29 Swapping Nodes in a Linked List Medium Linked List, Two Pointers LC