The NeetCode 150 LeetCode List

The NeetCode 150: an expansion of the Blind 75 into eighteen topic groups, from arrays and hashing through advanced graphs and two-dimensional dynamic programming.

150 problems
28 Easy
101 Medium
21 Hard
23 patterns

Where this list comes from

The NeetCode 150 is not ours. It is a published selection that people work through by name, and we reproduce it here by problem number, in the order the list itself uses. What we add is the solution: of the 150 entries below, 143 carry a complete Python solution with a worked example and its time and space complexity. The remaining 7 are either LeetCode Premium problems, whose statements are paywalled at the source, or problems our dataset holds no usable solution for. They are listed rather than quietly dropped, and the premium ones are marked in the tables.

The published list names 150 entries. All 150 resolve to a problem in this library and are listed below.

Every count on this page is computed from what the page renders, so the number in a heading is the number of rows under it. Nothing is padded to make a title's number come out right — that would be wrong in a way anyone who knows the list would spot in seconds.

All 150 problems, grouped by pattern

Each group is the pattern that most specifically solves those problems, so the list can be worked through a technique at a time instead of a problem at a time. Groups appear in the order the list itself introduces them.

Sorting (5)

#	Problem	Difficulty	Topics
217	Contains Duplicate	Easy	Array, Hash Table, Sorting
242	Valid Anagram	Easy	Hash Table, String, Sorting
49	Group Anagrams	Medium	Array, Hash Table, String +1
56	Merge Intervals	Medium	Array, Sorting
252	Meeting RoomsPremium	Easy	Array, Sorting

Hash Map (3)

#	Problem	Difficulty	Topics
1	Two Sum	Easy	Array, Hash Table
271	Encode and Decode StringsPremium	Medium	Design, Array, String
2013	Detect Squares	Medium	Design, Array, Hash Table +1

Heap / Priority Queue (10)

#	Problem	Difficulty	Topics
347	Top K Frequent Elements	Medium	Array, Hash Table, Divide and Conquer +5
703	Kth Largest Element in a Stream	Easy	Tree, Design, Binary Search Tree +3
1046	Last Stone Weight	Easy	Array, Heap (Priority Queue)
973	K Closest Points to Origin	Medium	Geometry, Array, Math +4
215	Kth Largest Element in an Array	Medium	Array, Divide and Conquer, Quickselect +2
621	Task Scheduler	Medium	Greedy, Array, Hash Table +3
295	Find Median from Data Stream	Hard	Design, Two Pointers, Data Stream +2
743	Network Delay Time	Medium	Depth-First Search, Breadth-First Search, Graph +2
787	Cheapest Flights Within K Stops	Medium	Depth-First Search, Breadth-First Search, Graph +3
1851	Minimum Interval to Include Each Query	Hard	Array, Binary Search, Sorting +2

Prefix Sum (2)

#	Problem	Difficulty	Topics
238	Product of Array Except Self	Medium	Array, Prefix Sum
253	Meeting Rooms IIPremium	Medium	Greedy, Array, Two Pointers +3

Matrix and Grid (8)

#	Problem	Difficulty	Topics
36	Valid Sudoku	Medium	Array, Hash Table, Matrix
74	Search a 2D Matrix	Medium	Array, Binary Search, Matrix
417	Pacific Atlantic Water Flow	Medium	Depth-First Search, Breadth-First Search, Array +1
994	Rotting Oranges	Medium	Breadth-First Search, Array, Matrix
286	Walls and GatesPremium	Medium	Breadth-First Search, Array, Matrix
48	Rotate Image	Medium	Array, Math, Matrix
54	Spiral Matrix	Medium	Array, Matrix, Simulation
73	Set Matrix Zeroes	Medium	Array, Hash Table, Matrix

Union-Find (9)

#	Problem	Difficulty	Topics
128	Longest Consecutive Sequence	Medium	Union Find, Array, Hash Table
200	Number of Islands	Medium	Depth-First Search, Breadth-First Search, Union Find +2
695	Max Area of Island	Medium	Depth-First Search, Breadth-First Search, Union Find +2
130	Surrounded Regions	Medium	Depth-First Search, Breadth-First Search, Union Find +2
684	Redundant Connection	Medium	Depth-First Search, Breadth-First Search, Union Find +1
323	Number of Connected Components in an Undirected GraphPremium	Medium	Depth-First Search, Breadth-First Search, Union Find +1
261	Graph Valid TreePremium	Medium	Depth-First Search, Breadth-First Search, Union Find +1
1584	Min Cost to Connect All Points	Medium	Union Find, Graph, Array +1
778	Swim in Rising Water	Hard	Depth-First Search, Breadth-First Search, Union Find +4

Two Pointers (8)

#	Problem	Difficulty	Topics
125	Valid Palindrome	Easy	Two Pointers, String
167	Two Sum II - Input Array Is Sorted	Medium	Array, Two Pointers, Binary Search
15	3Sum	Medium	Array, Two Pointers, Sorting
11	Container With Most Water	Medium	Greedy, Array, Two Pointers
5	Longest Palindromic Substring	Medium	Two Pointers, String, Dynamic Programming
647	Palindromic Substrings	Medium	Two Pointers, String, Dynamic Programming
763	Partition Labels	Medium	Greedy, Hash Table, Two Pointers +1
202	Happy Number	Easy	Hash Table, Math, Two Pointers

Stack (8)

#	Problem	Difficulty	Topics
42	Trapping Rain Water	Hard	Stack, Array, Two Pointers +2
20	Valid Parentheses	Easy	Stack, String
155	Min Stack	Medium	Stack, Design
150	Evaluate Reverse Polish Notation	Medium	Stack, Array, Math
739	Daily Temperatures	Medium	Stack, Array, Monotonic Stack
853	Car Fleet	Medium	Stack, Array, Sorting +1
84	Largest Rectangle in Histogram	Hard	Stack, Array, Monotonic Stack
678	Valid Parenthesis String	Medium	Stack, Greedy, String +1

Dynamic Programming (18)

#	Problem	Difficulty	Topics
121	Best Time to Buy and Sell Stock	Easy	Array, Dynamic Programming
70	Climbing Stairs	Easy	Memoization, Math, Dynamic Programming
746	Min Cost Climbing Stairs	Easy	Array, Dynamic Programming
198	House Robber	Medium	Array, Dynamic Programming
213	House Robber II	Medium	Array, Dynamic Programming
91	Decode Ways	Medium	String, Dynamic Programming
152	Maximum Product Subarray	Medium	Array, Dynamic Programming
416	Partition Equal Subset Sum	Medium	Array, Dynamic Programming
62	Unique Paths	Medium	Math, Dynamic Programming, Combinatorics
1143	Longest Common Subsequence	Medium	String, Dynamic Programming
309	Best Time to Buy and Sell Stock with Cooldown	Medium	Array, Dynamic Programming
518	Coin Change II	Medium	Array, Dynamic Programming
97	Interleaving String	Medium	String, Dynamic Programming
115	Distinct Subsequences	Hard	String, Dynamic Programming
72	Edit Distance	Medium	String, Dynamic Programming
312	Burst Balloons	Hard	Array, Dynamic Programming
10	Regular Expression Matching	Hard	Recursion, String, Dynamic Programming
53	Maximum Subarray	Medium	Array, Divide and Conquer, Dynamic Programming

Sliding Window (5)

#	Problem	Difficulty	Topics
3	Longest Substring Without Repeating Characters	Medium	Hash Table, String, Sliding Window
424	Longest Repeating Character Replacement	Medium	Hash Table, String, Sliding Window
567	Permutation in String	Medium	Hash Table, Two Pointers, String +1
76	Minimum Window Substring	Hard	Hash Table, String, Sliding Window
239	Sliding Window Maximum	Hard	Queue, Array, Sliding Window +2

Backtracking (11)

#	Problem	Difficulty	Topics
22	Generate Parentheses	Medium	String, Dynamic Programming, Backtracking
78	Subsets	Medium	Bit Manipulation, Array, Backtracking
39	Combination Sum	Medium	Array, Backtracking
46	Permutations	Medium	Array, Backtracking
90	Subsets II	Medium	Bit Manipulation, Array, Backtracking
40	Combination Sum II	Medium	Array, Backtracking
79	Word Search	Medium	Depth-First Search, Array, String +2
131	Palindrome Partitioning	Medium	String, Dynamic Programming, Backtracking
17	Letter Combinations of a Phone Number	Medium	Hash Table, String, Backtracking
51	N-Queens	Hard	Array, Backtracking
494	Target Sum	Medium	Array, Dynamic Programming, Backtracking

Monotonic Stack (6)

#	Problem	Difficulty	Topics
704	Binary Search	Easy	Array, Binary Search
875	Koko Eating Bananas	Medium	Array, Binary Search
153	Find Minimum in Rotated Sorted Array	Medium	Array, Binary Search
33	Search in Rotated Sorted Array	Medium	Array, Binary Search
4	Median of Two Sorted Arrays	Hard	Array, Binary Search, Divide and Conquer
300	Longest Increasing Subsequence	Medium	Array, Binary Search, Dynamic Programming

Binary Search (1)

#	Problem	Difficulty	Topics
981	Time Based Key-Value Store	Medium	Design, Hash Table, String +1

Linked List (11)

#	Problem	Difficulty	Topics
206	Reverse Linked List	Easy	Recursion, Linked List
21	Merge Two Sorted Lists	Easy	Recursion, Linked List
143	Reorder List	Medium	Stack, Recursion, Linked List +1
19	Remove Nth Node From End of List	Medium	Linked List, Two Pointers
138	Copy List with Random Pointer	Medium	Hash Table, Linked List
2	Add Two Numbers	Medium	Recursion, Linked List, Math
141	Linked List Cycle	Easy	Hash Table, Linked List, Two Pointers
146	LRU Cache	Medium	Design, Hash Table, Linked List +1
23	Merge k Sorted Lists	Hard	Linked List, Divide and Conquer, Heap (Priority Queue) +1
25	Reverse Nodes in k-Group	Hard	Recursion, Linked List
355	Design Twitter	Medium	Design, Hash Table, Linked List +1

Bit Manipulation (7)

#	Problem	Difficulty	Topics
287	Find the Duplicate Number	Medium	Bit Manipulation, Array, Two Pointers +1
136	Single Number	Easy	Bit Manipulation, Array
191	Number of 1 Bits	Easy	Bit Manipulation, Divide and Conquer
338	Counting Bits	Easy	Bit Manipulation, Dynamic Programming
190	Reverse Bits	Easy	Bit Manipulation, Divide and Conquer
268	Missing Number	Easy	Bit Manipulation, Array, Hash Table +3
371	Sum of Two Integers	Medium	Bit Manipulation, Math

Tree Traversal (15)

#	Problem	Difficulty	Topics
226	Invert Binary Tree	Easy	Tree, Depth-First Search, Breadth-First Search +1
104	Maximum Depth of Binary Tree	Easy	Tree, Depth-First Search, Breadth-First Search +1
543	Diameter of Binary Tree	Easy	Tree, Depth-First Search, Binary Tree
110	Balanced Binary Tree	Easy	Tree, Depth-First Search, Binary Tree
100	Same Tree	Easy	Tree, Depth-First Search, Breadth-First Search +1
572	Subtree of Another Tree	Easy	Tree, Depth-First Search, Binary Tree +2
235	Lowest Common Ancestor of a Binary Search Tree	Medium	Tree, Depth-First Search, Binary Search Tree +1
102	Binary Tree Level Order Traversal	Medium	Tree, Breadth-First Search, Binary Tree
199	Binary Tree Right Side View	Medium	Tree, Depth-First Search, Breadth-First Search +1
1448	Count Good Nodes in Binary Tree	Medium	Tree, Depth-First Search, Breadth-First Search +1
98	Validate Binary Search Tree	Medium	Tree, Depth-First Search, Binary Search Tree +1
230	Kth Smallest Element in a BST	Medium	Tree, Depth-First Search, Binary Search Tree +1
105	Construct Binary Tree from Preorder and Inorder Traversal	Medium	Tree, Array, Hash Table +2
124	Binary Tree Maximum Path Sum	Hard	Tree, Depth-First Search, Dynamic Programming +1
297	Serialize and Deserialize Binary Tree	Hard	Tree, Depth-First Search, Breadth-First Search +3

Trie (4)

#	Problem	Difficulty	Topics
208	Implement Trie (Prefix Tree)	Medium	Design, Trie, Hash Table +1
211	Design Add and Search Words Data Structure	Medium	Depth-First Search, Design, Trie +1
212	Word Search II	Hard	Trie, Array, String +2
139	Word Break	Medium	Trie, Memoization, Array +3

Breadth-First Search (3)

#	Problem	Difficulty	Topics
133	Clone Graph	Medium	Depth-First Search, Breadth-First Search, Graph +1
127	Word Ladder	Hard	Breadth-First Search, Hash Table, String
322	Coin Change	Medium	Breadth-First Search, Array, Dynamic Programming

Topological Sort (4)

#	Problem	Difficulty	Topics
207	Course Schedule	Medium	Depth-First Search, Breadth-First Search, Graph +1
210	Course Schedule II	Medium	Depth-First Search, Breadth-First Search, Graph +1
269	Alien DictionaryPremium	Hard	Depth-First Search, Breadth-First Search, Graph +3
329	Longest Increasing Path in a Matrix	Hard	Depth-First Search, Breadth-First Search, Graph +5

Depth-First Search (1)

#	Problem	Difficulty	Topics
332	Reconstruct Itinerary	Hard	Depth-First Search, Graph, Eulerian Circuit

Greedy (6)

#	Problem	Difficulty	Topics
55	Jump Game	Medium	Greedy, Array, Dynamic Programming
45	Jump Game II	Medium	Greedy, Array, Dynamic Programming
846	Hand of Straights	Medium	Greedy, Array, Hash Table +1
1899	Merge Triplets to Form Target Triplet	Medium	Greedy, Array
134	Gas Station	Medium	Greedy, Array
435	Non-overlapping Intervals	Medium	Greedy, Array, Dynamic Programming +1

Other (1)

#	Problem	Difficulty	Topics
57	Insert Interval	Medium	Array

Math and Number Theory (4)

#	Problem	Difficulty	Topics
66	Plus One	Easy	Array, Math
50	Pow(x, n)	Medium	Recursion, Math
43	Multiply Strings	Medium	Math, String, Simulation
7	Reverse Integer	Medium	Math

Other study lists

Blind 7575 problemsThe Blind 75: a 75-problem list assembled from the patterns that keep reappearing in technical interviews, grouped by topic. Every entry links to a Python solution with complexity analysis.Grind 7575 problemsThe Grind 75: the Blind 75 reworked into a week-by-week schedule that starts with the easiest high-yield problems and ends on the hard ones. Ordered for study, not by topic.LeetCode 7575 problemsLeetCode 75: the official study plan, seventy-five problems across twenty-two topic groups from array and string work up to monotonic stacks. Skewed easier than the Blind 75 and better as a first pass.Top Interview 150150 problemsTop Interview 150: the official interview-preparation list, a hundred and fifty problems covering every data structure and technique a technical screen is likely to reach for.

Or go by technique instead of by list: all LeetCode patterns · the full problem list.

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