Easy

1. 67. Add Binary
2. 9. Palindrome Number
3. 70. Climbing Stairs
4. 28. Find the Index of the First Occurrence in a String
5. 268. Missing Number
6. 125. Valid Palindrome
7. 412. FizzBuzz
8. 14. Longest Common Prefix
9. 169. Majority Element
10. 88. Merge two sorted arrays
11. 231. Power of Two
12. 26. Remove Duplicates from sorted array
13. 344. Reverse a String
14. 35. Search Insert Position
15. 1. Two Sum
16. 1207. Unique Number of Occurrences
17. 242. Valid Anagram
18. 20. Valid Paranthesis
19. 1394. Find Lucky Integer in an Array
20. 409. Longest Palindrome
21. 383. Ransom Note
22. 5. Valid Number
23. 459. Repeated Substring Pattern
24. 168. Excel Sheet Column Title
25. 171. Excel Sheet Column Number
26. 3304. Find the K-th Character in String Game I
27. 350. Intersection of Two Arrays II
28. 349. Intersection of Two Arrays
29. 290. Word Pattern
30. 3330. Find the Original Typed String I
31. 2769. Find the Maximum Achievable Number
32. 338. Counting Bits
33. 111. Minimum Depth of Binary Tree
34. 13. Roman to Integer
35. 594. Longest Harmonious Subsequence
36. 104. Maximum Depth of Binary Tree
37. 2404. Most Frequent Even Element
38. 169. Majority Element
39. 2099. Find Subsequence of Length K With the Largest Sum
40. 724. Find Pivot Index
41. 2215. Find the Difference of Two Arrays
42. 2656. Maximum Sum With Exactly K Elements
43. 2600. K Items With the Maximum Sum
44. 1837. Sum of Digits in Base K
45. 434. Number of Segments in a String
46. 389. Find the Difference
47. 387. First Unique Character in a String
48. 228. Summary Ranges
49. 136. Single Number
50. 121. Best Time to Buy and Sell Stock
51. 2200. Find All K-Distant Indices in an Array
52. 205. Isomorphic Strings
53. 2138. Divide a String Into Groups of Size k
54. 2379. Minimum Recolors to Get K Consecutive Black Blocks
55. 2965. Find Missing and Repeated Values
56. 2570. Merge Two 2D Arrays by Summing Values
57. 83. Remove Duplicates from Sorted List
58. 66. Plus One
59. 69. Sqrt(x)
60. 2873. Maximum Value of an Ordered Triplet I
61. 2206. Divide Array Into Equal Pairs
62. 2529. Maximum Count of Positive Integer and Negative Integer
63. 88. Merge Sorted Array
64. 2016. Maximum Difference Between Increasing Elements
65. 2900. Longest Unequal Adjacent Groups Subsequence I
66. 2566. Maximum Difference by Remapping a Digit
67. 3024. Type of Triangle
68. 2942. Find Words Containing Character
69. 3423. Maximum Difference Between Adjacent Elements in a Circular Array
70. 3392. Count Subarrays of Length Three With a Condition
71. 1295. Find Numbers with Even Number of Digits
72. 1128. Number of Equivalent Domino Pairs
73. 1920. Build Array from Permutation
74. 1550. Three Consecutive Odds
75. 3442. Maximum Difference Between Even and Odd Frequency I
76. 1484. Group Sold Products By The Date
77. 1399. Count Largest Group
78. 118. Pascal's Triangle
79. 2894. Divisible and Non-divisible Sums Difference
80. 3110. Score of a String
81. 2884. Modify Columns
82. 2879. Disfplay the First Three Rows
83. 2703. Return Length of Arguments Passed
84. 100. Same Tree
85. 1768. Merge Strings
86. 58. Length of Last Word
87. 27. Remove Element
88. 21. Merge Two Sorted Lists
89. 933. Number of Recent Calls
90. 1732. Find the Highest Altitude
91. 605. Can Place Flowers
92. 392. Is Subsequence
93. 643. Maximum Average Subarray I
94. 283. Move Zeroes
95. 217. Contains Duplicate
96. 2176. Count Equal and Divisible Pairs in an Array
97. 1431. Kids With the Greatest Number of Candies
98. 1071. Greatest Common Divisor of Strings
99. 485. Max Consecutive Ones
100. 344. Reverse String
101. 496. Next Greater Element I
102. 202. Happy Number

Medium

1. 2390. Removing stars from a string
2. 204. Count Primes
3. 49. Group Anagrams
4. 386. Lexicographical Numbers
5. 53. Maximum subarray sum
6. 189. Rotate Array
7. 75. Sort Colors
8. 2434. Using a robot to print the lexicographically smallest string
9. 26. Valid Sudoku
10. 176. Second Highest Salary
11. 3597. Partition String
12. 19. Remove Nth Node From End of List
13. 5. Longest Palindromic Substring
14. 347. Top K Frequent Elements
15. 299. Bulls and Cows
16. 29. Divide Two Integers
17. 1498. Number of Subsequences
18. 17. Letter Combinations of a Phone Number
19. 2095. Delete the Middle Node of a Linked List
20. 3085. Minimum Deletions to Make String K-Special
21. 2579. Count Total Number of Colored Cells
22. 2523. Closest Prime Numbers in Range
23. 2294. Partition Array Such That Maximum Difference Is K
24. 3443. Maximum Manhattan Distance After K Changes
25. 43. Multiply Strings
26. 50. Pow(x, n)
27. 2966. Divide Array Into Arrays With Max Difference
28. 2901. Longest Unequal Adjacent Groups Subsequence II
29. 1432. Max Difference You Can Get From Changing an Integer
30. 1456. Maximum Number of Vowels in a Substring of Given Length
31. 38. Count and Say
32. 48. Rotate Image
33. 3170. Lexicographically Minimum String After Removing Stars
34. 7. Reverse Integer
35. 1061. Lexicographically Smallest Equivalent String
36. 3403. Find the Lexicographically Largest String From the Box I
37. 3. Longest Substring Without Repeating Characters
38. 6. Zigzag Conversion
39. 2. Add Two Numbers
40. 8. String to Integer (atoi)
41. 1679. Max Number of K-Sum Pairs
42. 394. Decode String
43. 735. Asteroid Collision
44. 443. String Compression
45. 53. Maximum Subarray
46. 11. Container With Most Water
47. 165. Compare Version Numbers
48. 300. Longest Increasing Subsequence
49. 151. Reverse Words in a String
50. 238. Product of Array Except Self
51. 334. Increasing Triplet Subsequence
52. 560. Subarray Sum Equals K
53. 739. Daily Temperatures
54. 1865. Finding Pairs With a Certain Sum
55. 71. Simplify Path
56. 1353. Maximum Number of Events That Can Be Attended

Hard

1. 3307. Find the K-th Character in String Game II
2. 3333. Find the Original Typed String II
3. 2040. Kth Smallest Product of Two Sorted Arrays
4. 3405. Count the Number of Arrays with K Matching Adjacent Elements
5. 3445. Maximum Difference Between Even and Odd Frequency II
6. 440. K-th Smallest in Lexicographical Order

Generic

1. Check if a number is prime or not
2. Factorial of a number
3. Fibonacci Sequence
4. Sieve of Eratosthenes