Leetcode order table

ID	Question	Difficulty	Frequency	Data Structures	Algorithms
1	Two sum	2	5	Array + set	Sort + two pointers
2	Add two numbers	3	4	Linked List	Two pointers + math
3	Longest substring without repeating characters	3	2	String + hashtable	Two pointers
4	Median of two sorted Arrays	5	3	Array	Binary Search
5	Longest palindromic substring	4	2	String
6	Zigzag Conversion	3	1	String
7	Reverse integer	2	3		Math
8	String to INTEGER (atoi)	2	5	String	Math
9	Palindrome number	2	2		Math
10	Regular Expression matching	5	3	String	Recursion + dp
11	Container with most water	3	2	Array	Two pointers
12	Integer to Roman	3	4		Math
13	Roman to integer	2	4		Math
14	Longest Common prefix	2	1	String
15	3sum	3	5	Array	Two pointers
16	3sum closest	3	1	Array	Two pointers
17	Letter combinations of a phone number	3	3	String	DFS
18	4Sum	3	2	Array
19	Remove nth node from end of list	2	3	Linked List	Two pointers
20	Valid parentheses	2	5	String	Stack
21	Merge two sorted lists	2	5	Linked List	Sort + two pointers + merge
22	Generate parentheses	3	4	String	DFS
23	Merge K sorted lists	3	4	Linked List + heap	Sort + two pointers + merge
24	Swap nodes in pairs	2	4	Linked List
25	Reverse nodes in K-group	4	2	Linked List	Recursion + two pointers
26	Remove duplicates from sorted Array	1	3	Array	Two pointers
27	Remove Element	1	4	Array	Two pointers
28	Implement strstr ()	4	5	String	Two pointers + KMP + rolling hash
29	Divide two integers	4	3		Binary Search + math
30	Substring with concatenation of all words	3	1	String	Two pointers
31	Next Permutation	5	2	Array	Permutation
32	Longest valid parentheses	4	1	String	DP
33	Search in rotated sorted Array	4	3	Array	Binary Search
34	Search for a Range	4	3	Array	Binary Search
35	Search insert position	2	2	Array
36	Valid Sudoku	2	2	Array
37	Sudoku Solver	4	2	Array	DFS
38	Count and say	2	2	String	Two pointers
39	Combination sum	3	3	Array	Combination
40	Combination sum II	4	2	Array	Combination
41	First missing positive	5	2	Array	Sort
42	Trapping rain water	4	2	Array	Two pointers + Stack
43	Multiply strings	4	3	String	Two pointers + math
44	Wildcard matching	5	3	String	Recursion + dp + greedy
45	Jump Game II	4	2	Array
46	Permutations	3	4	Array	Permutation
47	Permutations II	4	2	Array	Permutation
48	Rotate Image	4	2	Array
49	Anagrams	3	4	String + hashtable
50	Pow (x, n)	3	5		Binary Search + math
51	N-queens	4	3	Array	DFS
52	N-Queens II	4	3	Array	DFS
53	Maximum subarray	3	3	Array	DP
54	Spiral Matrix	4	2	Array
55	Jump game	3	2	Array
56	Merge intervals	4	5	Array + linked list + red-black tree	Sort + merge
57	Insert Interval	4	5	Array + linked list + red-black tree	Sort + merge
58	Length of last word	1	1	String
59	Spiral matrix II	3	2	Array
60	Permutation sequence	5	1		Permutation + math
61	Rotate list	3	2	Linked List	Two pointers
62	Unique paths	2	3	Array	DP
63	Unique paths II	3	3	Array	DP
64	Minimum path sum	3	3	Array	DP
65	Valid number	2	5	String	Math
66	Plus one	1	2	Array	Math
67	Add binary	2	4	String	Two pointers + math
68	Text justification	4	2	String
69	SQRT (X)	4	4		Binary Search
70	Climbing stairs	2	5		DP
71	Simplify path	3	1	String	Stack
72	Edit distance	4	3	String	DP
73	Set matrix zeroes	3	5	Array
74	Search a 2D matrix	3	3	Array	Binary Search
75	Sort colors	4	2	Array	Sort + two pointers
76	Minimum window substring	4	2	String	Two pointers
77	Combinations	3	4		Combination
78	Subsets	3	4	Array	Recursion + combination
79	Word search	3	4	Array	DFS
80	Remove duplicates from sorted array II	2	2	Array	Two pointers
81	Search in rotated sorted array II	5	3	Array	Binary Search
82	Remove duplicates from sorted List II	3	3	Linked List	Recursion + two pointers
83	Remove duplicates from sorted list	1	3	Linked List
84	Largest rectangle in Histogram	5	2	Array	Stack
85	Maximal rectangle	5	1	Array	DP + Stack
86	Partition list	3	3	Linked List	Two pointers
87	Scramble string	5	2	String	Recursion + dp
88	Merge sorted Array	2	5	Array	Two pointers + merge
89	Gray Code	4	2		Combination
90	Subsets II	4	2	Array	Recursion + combination
91	Decode ways	3	4	String	Recursion + dp
92	Reverse Linked List II	3	2	Linked List	Two pointers
93	Restore IP addresses	3	3	String	DFS
94	Binary Tree inorder Traversal	4	3	Tree + hashtable	Recursion + Morris + Stack
95	Unique Binary Search Trees II	4	1	Tree	DP + DFS
96	Unique Binary Search Trees	3	1	Tree	DP
97	Interleaving string	5	2	String	Recursion + dp
98	Validate Binary Search Tree	3	5	Tree	DFS
99	Recover Binary Search Tree	4	2	Tree	DFS
100	Same Tree	1	1	Tree	DFS
101	Symmetric tree	1	2	Tree	DFS
102	Binary Tree level order traversal	3	4	Tree	BFS
103	Binary Tree zigzag level order traversal	4	3	Queue + tree	BFS + Stack
104	Maximum depth of Binary Tree	1	1	Tree	DFS
105	Construct binary tree from preorder and inorder tr	3	3	Array + tree	DFS
106	Construct binary tree from inorder and postorder t	3	3	Array + tree	DFS
107	Binary Tree level order traversal II	3	1	Tree	BFS
108	Convert sorted array to Binary Search Tree	2	3	Tree	DFS
109	Convert sorted list to Binary Search Tree	4	3	Linked List	Recursion + two pointers
110	Balanced Binary Tree	1	2	Tree	DFS
111	Minimum depth of Binary Tree	1	1	Tree	DFS
112	Path sum	1	3	Tree	DFS
113	Path sum II	2	2	Tree	DFS
114	Flatten binary tree to linked list	3	3	Tree	Recursion + Stack
115	Distinct subsequences	4	2	String	DP
116	Populating next right pointers in each node	3	3	Tree	DFS
117	Populating next right pointers in each node II	4	2	Tree	DFS
118	Pascal's Triangle	2	1	Array
119	Pascal's triangle II	2	1	Array
120	Triangle	3	1	Array	DP
121	Best time to buy and buy stock	2	1	Array	DP
122	Best time to buy and stock Stock II	3	1	Array	Greedy
123	Best time to buy and buy stock III	4	1	Array	DP
124	Binary Tree maximum path sum	4	2	Tree	DFS
125	Valid palindrome	2	5	String	Two pointers
126	Word ladder II	1	1
127	Word ladder	3	5	Graph	BFS + Shortest Path
128	Longest consecutive sequence	4	3	Array
129	Sum root to leaf numbers	2	4	Tree	DFS
130	Surrounded regions	4	3	Array	BFS + DFS
131	Palindrome partitioning	3	4	String	DFS
132	Palindrome partitioning II	4	3	String	DP

Leetcode order table