The LeetCode 75 Study Plan

LeetCode 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.

75 problems
22 Easy
53 Medium
0 Hard
20 patterns

Where this list comes from

The LeetCode 75 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 75 entries below, 75 carry a complete Python solution with a worked example and its time and space complexity.

The published list names 75 entries. All 75 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 75 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.

Two Pointers (9)

#	Problem	Difficulty	Topics
1768	Merge Strings Alternately	Easy	Two Pointers, String
345	Reverse Vowels of a String	Easy	Two Pointers, String
151	Reverse Words in a String	Medium	Two Pointers, String
443	String Compression	Medium	Two Pointers, String
283	Move Zeroes	Easy	Array, Two Pointers
392	Is Subsequence	Easy	Two Pointers, String, Dynamic Programming
11	Container With Most Water	Medium	Greedy, Array, Two Pointers
1679	Max Number of K-Sum Pairs	Medium	Array, Hash Table, Two Pointers +1
2300	Successful Pairs of Spells and Potions	Medium	Array, Two Pointers, Binary Search +1

Math and Number Theory (1)

#	Problem	Difficulty	Topics
1071	Greatest Common Divisor of Strings	Easy	Math, String

Other (1)

#	Problem	Difficulty	Topics
1431	Kids With the Greatest Number of Candies	Easy	Array

Greedy (5)

#	Problem	Difficulty	Topics
605	Can Place Flowers	Easy	Greedy, Array
334	Increasing Triplet Subsequence	Medium	Greedy, Array
714	Best Time to Buy and Sell Stock with Transaction Fee	Medium	Greedy, Array, Dynamic Programming
435	Non-overlapping Intervals	Medium	Greedy, Array, Dynamic Programming +1
452	Minimum Number of Arrows to Burst Balloons	Medium	Greedy, Array, Sorting

Prefix Sum (3)

#	Problem	Difficulty	Topics
238	Product of Array Except Self	Medium	Array, Prefix Sum
1732	Find the Highest Altitude	Easy	Array, Prefix Sum
724	Find Pivot Index	Easy	Array, Prefix Sum

Sliding Window (4)

#	Problem	Difficulty	Topics
643	Maximum Average Subarray I	Easy	Array, Sliding Window
1456	Maximum Number of Vowels in a Substring of Given Length	Medium	String, Sliding Window
1004	Max Consecutive Ones III	Medium	Array, Binary Search, Prefix Sum +1
1493	Longest Subarray of 1's After Deleting One Element	Medium	Array, Dynamic Programming, Sliding Window

Hash Map (2)

#	Problem	Difficulty	Topics
2215	Find the Difference of Two Arrays	Easy	Array, Hash Table
1207	Unique Number of Occurrences	Easy	Array, Hash Table

Sorting (1)

#	Problem	Difficulty	Topics
1657	Determine if Two Strings Are Close	Medium	Hash Table, String, Counting +1

Matrix and Grid (3)

#	Problem	Difficulty	Topics
2352	Equal Row and Column Pairs	Medium	Array, Hash Table, Matrix +1
1926	Nearest Exit from Entrance in Maze	Medium	Breadth-First Search, Array, Matrix
994	Rotting Oranges	Medium	Breadth-First Search, Array, Matrix

Stack (7)

#	Problem	Difficulty	Topics
2390	Removing Stars From a String	Medium	Stack, String, Simulation
735	Asteroid Collision	Medium	Stack, Array, Simulation
394	Decode String	Medium	Stack, Recursion, String
933	Number of Recent Calls	Easy	Design, Queue, Data Stream
649	Dota2 Senate	Medium	Greedy, Queue, String
739	Daily Temperatures	Medium	Stack, Array, Monotonic Stack
901	Online Stock Span	Medium	Stack, Design, Data Stream +1

Linked List (4)

#	Problem	Difficulty	Topics
2095	Delete the Middle Node of a Linked List	Medium	Linked List, Two Pointers
328	Odd Even Linked List	Medium	Linked List
206	Reverse Linked List	Easy	Recursion, Linked List
2130	Maximum Twin Sum of a Linked List	Medium	Stack, Linked List, Two Pointers

Tree Traversal (10)

#	Problem	Difficulty	Topics
104	Maximum Depth of Binary Tree	Easy	Tree, Depth-First Search, Breadth-First Search +1
872	Leaf-Similar Trees	Easy	Tree, Depth-First Search, Binary Tree
1448	Count Good Nodes in Binary Tree	Medium	Tree, Depth-First Search, Breadth-First Search +1
437	Path Sum III	Medium	Tree, Depth-First Search, Binary Tree
1372	Longest ZigZag Path in a Binary Tree	Medium	Tree, Depth-First Search, Dynamic Programming +1
236	Lowest Common Ancestor of a Binary Tree	Medium	Tree, Depth-First Search, Binary Tree
199	Binary Tree Right Side View	Medium	Tree, Depth-First Search, Breadth-First Search +1
1161	Maximum Level Sum of a Binary Tree	Medium	Tree, Depth-First Search, Breadth-First Search +1
700	Search in a Binary Search Tree	Easy	Tree, Binary Search Tree, Binary Tree
450	Delete Node in a BST	Medium	Tree, Binary Search Tree, Binary Tree

Breadth-First Search (2)

#	Problem	Difficulty	Topics
841	Keys and Rooms	Medium	Depth-First Search, Breadth-First Search, Graph
1466	Reorder Routes to Make All Paths Lead to the City Zero	Medium	Depth-First Search, Breadth-First Search, Graph

Union-Find (2)

#	Problem	Difficulty	Topics
547	Number of Provinces	Medium	Depth-First Search, Breadth-First Search, Union Find +1
399	Evaluate Division	Medium	Depth-First Search, Breadth-First Search, Union Find +4

Heap / Priority Queue (4)

#	Problem	Difficulty	Topics
215	Kth Largest Element in an Array	Medium	Array, Divide and Conquer, Quickselect +2
2336	Smallest Number in Infinite Set	Medium	Design, Hash Table, Ordered Set +1
2542	Maximum Subsequence Score	Medium	Greedy, Array, Sorting +1
2462	Total Cost to Hire K Workers	Medium	Array, Two Pointers, Simulation +1

Monotonic Stack (3)

#	Problem	Difficulty	Topics
374	Guess Number Higher or Lower	Easy	Binary Search, Interactive
162	Find Peak Element	Medium	Array, Binary Search
875	Koko Eating Bananas	Medium	Array, Binary Search

Backtracking (2)

#	Problem	Difficulty	Topics
17	Letter Combinations of a Phone Number	Medium	Hash Table, String, Backtracking
216	Combination Sum III	Medium	Array, Backtracking

Dynamic Programming (7)

#	Problem	Difficulty	Topics
1137	N-th Tribonacci Number	Easy	Memoization, Math, Dynamic Programming
746	Min Cost Climbing Stairs	Easy	Array, Dynamic Programming
198	House Robber	Medium	Array, Dynamic Programming
790	Domino and Tromino Tiling	Medium	Dynamic Programming
62	Unique Paths	Medium	Math, Dynamic Programming, Combinatorics
1143	Longest Common Subsequence	Medium	String, Dynamic Programming
72	Edit Distance	Medium	String, Dynamic Programming

Bit Manipulation (3)

#	Problem	Difficulty	Topics
338	Counting Bits	Easy	Bit Manipulation, Dynamic Programming
136	Single Number	Easy	Bit Manipulation, Array
1318	Minimum Flips to Make a OR b Equal to c	Medium	Bit Manipulation

Trie (2)

#	Problem	Difficulty	Topics
208	Implement Trie (Prefix Tree)	Medium	Design, Trie, Hash Table +1
1268	Search Suggestions System	Medium	Trie, Array, String +3

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.NeetCode 150150 problemsThe NeetCode 150: an expansion of the Blind 75 into eighteen topic groups, from arrays and hashing through advanced graphs and two-dimensional dynamic programming.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.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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