1. Check For BST
Naive O(N^2) O(H) Assigning Ranges O(N) O(H) Storing Inorder Traversal O(N) O(N) Without Storing Inorder Traversal O(N) O(H)
2. Reverse a linked list
Naive O(N) O(N) Changing the arrows O(N) O(1) Recursive with Global O(N) O(N) Recurssive without Global O(N) O(N)
3. Finding middle element in a linked list
Naive Two Traversal O(N) O(1) Fast Slow Pointers Iterative O(N) O(1) Fast Slow Pointers Recurssive O(N) O(N)
4. Longest Palindrome in a String
Bottom-Up DP O(N^2) O(N^2)
5. Check if Linked List is Palindrome
6. Get minimum element from stack
7. Intersection Point in Y Shapped Linked Lists
8. Delete without head pointer
9. Determine if Two Trees are Identical
10. BFS of graph
11. Diameter of Binary Tree
12. Detect cycle in a directed graph
13. Mirror Tree
14. Add two numbers represented by linked lists
15. Level order traversal in spiral form
16. Reverse a Linked List in groups of given size
17. Search in a Rotated Array
18. Boundary Traversal of binary tree
19. Level order traversal
20. Longest Common Substring
21. Lowest Common Ancestor in a BST
22. Merge two sorted linked lists
23. Root to leaf path sum
24. Implement Atoi
25. Count distinct elements in every window
26. Maximum Path Sum between 2 Leaf Nodes
27. Connect Nodes at Same Level
28. First non-repeating character in a stream
29. Pairwise swap elements of a linked list
30. Longest Distinct characters in string
31. Queue using two Stacks
32. The Celebrity Problem
33. Multiply two strings
34. Circular tour
35. Binary Tree to DLL
36. Level order traversal Line by Line
37. Lowest Common Ancestor in a Binary Tree
38. Relative Sorting
39. Find the number of islands
40. Flattening a Linked List
41. Insert a node in a BST
42. Implement strstr
43. Merge Sort
44. Square root
45. Validate an IP Address
46. Topological sort
47. Given a linked list of 0s, 1s and 2s, sort i
48. Implement Stack using Linked List
49. Minimum element in a sorted and rotated arra
50. Check if subtree
51. Word Boggle
52. Implement two stacks in an array
53. Reverse Level Order Traversal
54. K distance from root
55. Minimum element in BST
56. Interleaved Strings
57. Intersection of two sorted Linked lists
58. Sorted insert for circular linked list
59. Check If Circular Linked List
60. Kadane's Algorithm
61. Sort an array of 0s, 1s and 2s
62. Ease the Array
63. Intersection of Two Linked Lists
64. Delete Middle of Linked List
65. Stock buy and sell
66. Delete N nodes after M nodes of a linked lis
67. Factorials of large numbers
68. Column name from a given column number
69. Overlapping rectangles
70. Serialize and Deserialize a Binary Tree
71. Print BST elements in given range
72. Find the fine
73. Construct Tree from Inorder & Preorder
74. Reverse words in a given string
75. Transform to Sum Tree
76. Reorder List
77. Check if Tree is Isomorphic
78. Merge k Sorted Arrays
79. Majority Element
80. Run Length Encoding
81. Print Pattern
82. Clone a linked list with next and random poi
83. Nearest multiple of 10
84. Max rectangle
85. Knight Walk
86. Maximum in Struct Array
87. Count Number of SubTrees having given Sum
88. Merge Without Extra Space
89. Fixing Two nodes of a BST
90. Construct Binary Tree from Parent Array
91. Merge Without Extra Space
92. Merge Sort for Linked List
93. Box Stacking
94. Inversion of array
95. Merge two BST 's
96. A Simple Fraction
97. Missing number in array
98. Alien Dictionary
99. Unit Area of largest region of 1's
100. Union of Two Linked Lists
101. Merge 2 sorted linked list in reverse order
102. Buildings receiving sunlight
103. Boolean Parenthesization
104. Spirally traversing a matrix
105. Maximum Product Subarray
106. Phone directory
107. Convert to Roman No
108. 0 - 1 Knapsack Problem
109. Sum of Leaf Nodes at Min Level
110. Reverse each word in a given string
111. longest substring containing '1'
112. Node at distance
113. Common elements
114. Longest Even Length Substring
115. Kth smallest element
116. Stock buy and sell
117. URLify a given string
118. Match specific pattern
119. Non Repeating Character
120. Decode the pattern
121. Subsets
122. Unit Area of largest region of 1's
123. Delete nodes greater than k
124. Length of longest palindrome in linked list
125. Coin Change
126. Lucky Numbers
127. Longest Palindrome Substring
128. String Ignorance
129. Rotate by 90 degree
130. Difficulty of sentence
131. Find the string in grid
132. k largest elements
133. Remove common characters and concatenate
134. Rotate by 90 degree
135. Arranging the array
136. Solve the Sudoku
137. K largest elements
138. Maximize The Array
139. Find All Four Sum Numbers
140. Travelling Salesman Problem
141. Key Pair
142. Word Boggle
143. Longest Palindromic Substring in Linear Time
144. Replace the Bit
145. Word Wrap
146. Zero Sum Subarrays
147. Brackets in Matrix Chain Multiplication
148. Generate Grey Code Sequences
149. Largest Number formed from an Array
150. Find median in a stream
151. Rotten Oranges
152. Remove Duplicates
153. Closest Number
154. Finding Number
155. Subsets
156. Relative Sorting
157. Optimal Strategy For A Game
158. RegEx matching
159. Combination Sum
160. Consecutive 1's not allowed
161. Finding the numbers
162. Roman Number to Integer
163. Word Break
164. Number of paths
165. Shortest Common Supersequence
166. Perfect Sum Problem
167. Is Binary Number Multiple of 3
168. Arithmetic Progression
169. Two numbers with sum closest to zero
170. Find position of set bit
171. Longest Bitonic subsequence
172. Count Occurences of Anagrams
173. Sum of two large numbers
174. Add Binary Strings
175. Remove all duplicates from a given string
176. Mobile numeric keypad
177. Palindrome numbers
178. Tic Tac Toe
179. Design a tiny URL or URL shortener
180. Integer to Words
181. Next Smallest Palindrome
182. Minimum Points To Reach Destination
183. Binary representation
184. Strictly Increasing Array
185. Sort in specific order
186. Day of the week
187. Maximum no of 1's row
188. Minimize string value
189. Nth item through sum
190. Next greater number set digits
191. Carry counter
192. Transform the array
193. String comparison