Microsoft

#	Title	Difficulty	Frequency
1	Two Sum	Easy	7.06
2	Add Two Numbers	Medium	3.81
3	Longest Substring Without Repeating Characters	Medium	2.44
4	Median of Two Sorted Arrays	Hard	1.04
5	Longest Palindromic Substring	Medium	12.14
9	Palindrome Number	Easy	0.47
11	Container With Most Water	Medium	15.05
13	Roman to Integer	Easy	10.46
15	3Sum	Medium	1.30
19	Remove Nth Node From End of List	Medium	0.99
20	Valid Parentheses	Easy	0.84
21	Merge Two Sorted Lists	Easy	3.89
22	Generate Parentheses	Medium	5.70
23	Merge k Sorted Lists	Hard	4.50
25	Reverse Nodes in k-Group	Hard	19.09
32	Longest Valid Parentheses	Hard	3.59
41	First Missing Positive	Hard	6.07
42	Trapping Rain Water	Hard	2.75
49	Group Anagrams	Medium	9.83
53	Maximum Subarray	Medium	6.15
54	Spiral Matrix	Medium	9.69
55	Jump Game	Medium	1.01
67	Add Binary	Easy	1.84
73	Set Matrix Zeroes	Medium	1.30
88	Merge Sorted Array	Easy	0.50
101	Symmetric Tree	Easy	1.57
105	Construct Binary Tree from Preorder and Inorder Traversal	Medium	2.33
114	Flatten Binary Tree to Linked List	Medium	3.34
121	Best Time to Buy and Sell Stock	Easy	0.81
122	Best Time to Buy and Sell Stock II	Medium	5.35
146	LRU Cache	Medium	2.09
152	Maximum Product Subarray	Medium	1.45
153	Find Minimum in Rotated Sorted Array	Medium	3.57
168	Excel Sheet Column Title	Easy	6.78
171	Excel Sheet Column Number	Easy	6.54
175	Combine Two Tables	Easy	2.25
200	Number of Islands	Medium	5.78
205	Isomorphic Strings	Easy	1.72
206	Reverse Linked List	Easy	1.44
210	Course Schedule II	Medium	2.83
215	Kth Largest Element in an Array	Medium	5.66
217	Contains Duplicate	Easy	2.93
224	Basic Calculator	Hard	16.31
227	Basic Calculator II	Medium	8.39
234	Palindrome Linked List	Easy	6.01
239	Sliding Window Maximum	Hard	8.08
242	Valid Anagram	Easy	1.16
273	Integer to English Words	Hard	29.08
287	Find the Duplicate Number	Medium	1.28
300	Longest Increasing Subsequence	Medium	1.41
319	Bulb Switcher	Medium	11.54
328	Odd Even Linked List	Medium	3.22
347	Top K Frequent Elements	Medium	0.98
419	Battleships in a Board	Medium	19.97
451	Sort Characters By Frequency	Medium	6.26
473	Matchsticks to Square	Medium	18.49
542	01 Matrix	Medium	15.20
560	Subarray Sum Equals K	Medium	10.57
733	Flood Fill	Easy	3.15
853	Car Fleet	Medium	4.98
863	All Nodes Distance K in Binary Tree	Medium	6.70
912	Sort an Array	Medium	3.25
951	Flip Equivalent Binary Trees	Medium	24.21
981	Time Based Key-Value Store	Medium	4.60
1027	Longest Arithmetic Subsequence	Medium	11.03
1405	Longest Happy String	Medium	26.65
1209	Remove All Adjacent Duplicates in String II	Medium	13.44
1239	Maximum Length of a Concatenated String with Unique Characters	Medium	22.07
1822	Sign of the Product of an Array	Easy	19.25