Arrays & Hashing

LeetCode ID	Difficulty	Problem	Solutions
217	Easy	Contains Duplicate	C++ • Go • Java • Python
242	Easy	Valid Anagram	C++ • Go • Java • Python
1	Easy	Two Sum	C++ • Go • Java • Python
49	Medium	Group Anagrams	C++ • Go • Java • Python
347	Medium	Top K Frequent Elements	C++ • Go • Java • Python
238	Medium	Product of Array Except Self	C++ • Go • Java • Python
36	Medium	Valid Sudoku	C++ • Go • Java • Python
128	Medium	Longest Consecutive Sequence	C++ • Go • Java • Python

Two Pointers

LeetCode ID	Difficulty	Problem	Solutions
125	Easy	Valid Palindrome	C++ • Go • Java • Python
167	Medium	Two Sum II	C++ • Go • Java • Python
15	Medium	3Sum	C++ • Go • Java • Python
11	Medium	Container with Most Water	C++ • Go • Java • Python
42	Hard	Trapping Rain Water	C++ • Go • Java • Python

Sliding Window

LeetCode ID	Difficulty	Problem	Solutions
121	Easy	Best Time to Buy & Sell Stock	C++ • Go • Java • Python
3	Medium	Longest Substring Without Repeating Characters	C++ • Go • Java • Python
424	Medium	Longest Repeating Character Replacement	C++ • Go • Java • Python
567	Medium	Permutation in String	C++ • Go • Java • Python
76	Hard	Minimum Window Substring	C++ • Go • Java • Python
239	Hard	Sliding Window Maximum	C++ • Go • Java • Python

Stack

LeetCode ID	Difficulty	Problem	Solutions
20	Easy	Valid Parentheses	C++ • Go • Java • Python
155	Medium	Min Stack	C++ • Go • Java • Python
150	Medium	Evaluate Reverse Polish Notation	C++ • Go • Java • Python
22	Medium	Generate Parentheses	C++ • Go • Java • Python
739	Medium	Daily Temperatures	C++ • Go • Java • Python
853	Medium	Car Fleet	C++ • Go • Java • Python
84	Hard	Largest Rectangle in Histogram	C++ • Go • Java • Python

Binary Search

LeetCode ID	Difficulty	Problem	Solutions
704	Easy	Binary Search	C++ • Go • Java • Python
74	Medium	Search a 2D Matrix	C++ • Go • Java • Python
875	Medium	Koko Eating Bananas	C++ • Go • Java • Python
33	Medium	Search in Rotated Sorted Array	C++ • Go • Java • Python
153	Medium	Find Minimum in Rotated Sorted Array	C++ • Go • Java • Python
981	Medium	Time Based Key-Value Store	C++ • Go • Java • Python
4	Hard	Median of Two Sorted Arrays	C++ • Go • Java • Python

Linked List

LeetCode ID	Difficulty	Problem	Solutions
206	Easy	Reverse Linked List	C++ • Go • Java • Python
21	Easy	Merge Two Sorted Lists	C++ • Go • Java • Python
141	Easy	Linked List Cycle	C++ • Go • Java • Python
143	Medium	Reorder List	C++ • Go • Java • Python
19	Medium	Remove Nth Node From End of List	C++ • Go • Java • Python
2	Medium	Add Two Numbers	C++ • Go • Java • Python
287	Medium	Find the Duplicate Number	C++ • Go • Java • Python
146	Medium	LRU Cache	C++ • Go • Java • Python
23	Hard	Merge k Sorted Lists	C++ • Go • Java • Python
25	Hard	Reverse Nodes in k-Group	C++ • Go • Java • Python

Trees

LeetCode ID	Difficulty	Problem	Solutions
226	Easy	Invert Binary Tree	C++ • Go • Java • Python
104	Easy	Maximum Depth of Binary Tree	C++ • Go • Java • Python
543	Easy	Diameter of Binary Tree	C++ • Go • Java • Python
110	Easy	Balanced Binary Tree	C++ • Go • Java • Python
100	Easy	Same Tree	C++ • Go • Java • Python
572	Easy	Subtree Of Another Tree	C++ • Go • Java • Python
235	Medium	Lowest Common Ancestor Of A Binary Search Tree	C++ • Go • Java • Python
102	Medium	Binary Tree Level Order Traversal	C++ • Go • Java • Python
199	Medium	Binary Tree Right Side View	C++ • Go • Java • Python
1448	Medium	Count Good Nodes In Binary Tree	C++ • Go • Java • Python
98	Medium	Validate Binary Search Tree	C++ • Go • Java • Python
230	Medium	Kth Smallest Element In A Bst	C++ • Go • Java • Python
105	Medium	Construct Binary Tree From Preorder And Inorder Traversal	C++ • Go • Java • Python
124	Hard	Binary Tree Maximum Path Sum	C++ • Go • Java • Python

Tries

LeetCode ID	Difficulty	Problem	Solutions
208	Medium	Implement Trie Prefix Tree	C++ • Go • Java • Python
211	Medium	Design Add And Search Words Data Structure	C++ • Go • Java • Python
212	Hard	Word Search Ii	C++ • Go • Java • Python

Backtracking

LeetCode ID	Difficulty	Problem	Solutions
78	Medium	Subsets	C++ • Go • Java • Python
39	Medium	Combination Sum	C++ • Go • Java • Python
46	Medium	Permutations	C++ • Go • Java • Python
90	Medium	Subsets II	C++ • Go • Java • Python
40	Medium	Combination Sum II	C++ • Go • Java • Python
79	Medium	Word Search	C++ • Go • Java • Python
131	Medium	Palindrome Partitioning	C++ • Go • Java • Python
17	Medium	Letter Combinations Of A Phone Number	C++ • Go • Java • Python
51	Hard	N Queens	C++ • Go • Java • Python

Heap

LeetCode ID	Difficulty	Problem	Solutions
703	Easy	Kth Largest Element In A Stream	C++ • Go • Java • Python
1064	Easy	Last Stone Weight	C++ • Go • Java • Python
973	Medium	K Closest Points To Origin	C++ • Go • Java • Python
215	Medium	Kth Largest Element In An Array	C++ • Go • Java • Python
621	Medium	Task Scheduler	C++ • Go • Java • Python
355	Medium	Design Twitter	C++ • Go • Java • Python
295	Hard	Find Median From Data Stream	C++ • Go • Java • Python

Graph

LeetCode ID	Difficulty	Problem	Solutions
200	Medium	Number Of Islands	C++ • Go • Java • Python
695	Medium	Max Area Of Island	C++ • Go • Java • Python