200+ Coding Questions Asked in Service-Based Companies – The Ultimate Practice List

✅ How to Use This List

• Don’t aim to finish all 200 in one week.

• Pick 2–3 per day and focus on understanding the logic.

• Use any language you’re comfortable with.

• Start from Easy → Medium → Interview level.
  
  

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🔹 Arrays (25 Questions)

1. Two Sum – TCS
   
   

2. Best Time to Buy and Sell Stock – Wipro
   
   

3. Contains Duplicate – Infosys
   
   

4. Product of Array Except Self – Capgemini
   
   

5. Maximum Subarray – Cognizant
   
   

6. Maximum Product Subarray – Infosys
   
   

7. Find Minimum in Rotated Sorted Array – Wipro
   
   

8. Search in Rotated Sorted Array – TCS
   
   

9. 3Sum – Capgemini
   
   

10. Container With Most Water – Infosys
    
    

11. Majority Element – Cognizant
    
    

12. Rotate Array – Wipro
    
    

13. Spiral Matrix – Infosys
    
    

14. Set Matrix Zeroes – Capgemini
    
    

15. Pascal’s Triangle – TCS
    
    

16. Kth Largest Element in an Array – Infosys
    
    

17. Merge Intervals – Wipro
    
    

18. Insert Interval – Cognizant
    
    

19. Summary Ranges – Infosys
    
    

20. Missing Number – Capgemini
    
    

21. Find the Duplicate Number – Wipro
    
    

22. Minimum Size Subarray Sum – TCS
    
    

23. Move Zeroes – Infosys
    
    

24. Find All Numbers Disappeared in an Array – Capgemini
    
    

25. Maximum Average Subarray I – Cognizant
    
    

 

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🔹 Strings (25 Questions)

26. Valid Anagram – Infosys
    
    

27. Longest Common Prefix – TCS
    
    

28. Implement strStr() – Wipro
    
    

29. Reverse String – Capgemini
    
    

30. Reverse Words in a String – Cognizant
    
    

31. String Compression – Infosys
    
    

32. Is Subsequence – Wipro
    
    

33. Group Anagrams – TCS
    
    

34. Valid Palindrome – Capgemini
    
    

35. Longest Palindromic Substring – Infosys
    
    

36. Count and Say – Cognizant
    
    

37. First Unique Character in a String – Wipro
    
    

38. Add Binary – Infosys
    
    

39. Multiply Strings – TCS
    
    

40. Minimum Window Substring – Capgemini
    
    

41. Zigzag Conversion – Cognizant
    
    

42. Roman to Integer – Infosys
    
    

43. Integer to Roman – Wipro
    
    

44. String to Integer (atoi) – TCS
    
    

45. Length of Last Word – Capgemini
    
    

46. Longest Substring Without Repeating Characters – Infosys
    
    

47. Check If Two String Arrays are Equivalent – Cognizant
    
    

48. Valid Parentheses – Wipro
    
    

49. Remove All Adjacent Duplicates In String – Infosys
    
    

50. Reverse Vowels of a String – Capgemini
    
    

🔹 Linked Lists (25 Questions)

51. Reverse Linked List – TCS
    
    

52. Merge Two Sorted Lists – Infosys
    
    

53. Remove Nth Node From End of List – Wipro
    
    

54. Linked List Cycle – Capgemini
    
    

55. Palindrome Linked List – Cognizant
    
    

56. Intersection of Two Linked Lists – Infosys
    
    

57. Add Two Numbers – Wipro
    
    

58. Flatten a Multilevel Doubly Linked List – TCS
    
    

59. Copy List with Random Pointer – Capgemini
    
    

60. Swap Nodes in Pairs – Cognizant
    
    

61. Rotate List – Infosys
    
    

62. Remove Linked List Elements – Wipro
    
    

63. Delete Node in a Linked List – TCS
    
    

64. Odd Even Linked List – Capgemini
    
    

65. Reverse Nodes in k-Group – Cognizant
    
    

66. Partition List – Infosys
    
    

67. Remove Duplicates from Sorted List – Wipro
    
    

68. Sort List – TCS
    
    

69. Merge k Sorted Lists – Capgemini
    
    

70. Split Linked List in Parts – Cognizant
    
    

71. Next Greater Node In Linked List – Infosys
    
    

72. Linked List Cycle II – Wipro
    
    

73. Design Linked List – TCS
    
    

74. Middle of the Linked List – Capgemini
    
    

75. Remove Duplicates from Sorted List II – Cognizant
    
    

🔹 Trees (25 Questions)

76. Maximum Depth of Binary Tree – TCS
    
    

77. Same Tree – Infosys
    
    

78. Invert Binary Tree – Wipro
    
    

79. Binary Tree Level Order Traversal – Capgemini
    
    

80. Symmetric Tree – Cognizant
    
    

81. Balanced Binary Tree – Infosys
    
    

82. Path Sum – Wipro
    
    

83. Maximum Path Sum – TCS
    
    

84. Construct Binary Tree from Preorder and Inorder Traversal – Capgemini
    
    

85. Validate Binary Search Tree – Cognizant
    
    

86. Lowest Common Ancestor of a Binary Tree – Infosys
    
    

87. Binary Tree Right Side View – Wipro
    
    

88. Binary Tree Zigzag Level Order Traversal – TCS
    
    

89. Convert Sorted Array to Binary Search Tree – Capgemini
    
    

90. Sum of Left Leaves – Cognizant
    
    

91. Binary Tree Inorder Traversal – Infosys
    
    

92. Serialize and Deserialize Binary Tree – Wipro
    
    

93. Populating Next Right Pointers in Each Node – TCS
    
    

94. Find Duplicate Subtrees – Capgemini
    
    

95. Sum Root to Leaf Numbers – Cognizant
    
    

96. Recover Binary Search Tree – Infosys
    
    

97. Binary Search Tree Iterator – Wipro
    
    

98. All Nodes Distance K in Binary Tree – TCS
    
    

99. Flatten Binary Tree to Linked List – Capgemini
    
    

100. Kth Smallest Element in a BST – Cognizant
     
     

🔹 Recursion & Backtracking (15 Questions)

101. Permutations – TCS
     
     

102. Combinations – Wipro
     
     

103. Subsets – Infosys
     
     

104. Letter Combinations of a Phone Number – Capgemini
     
     

105. Combination Sum – Cognizant
     
     

106. Generate Parentheses – Infosys
     
     

107. Word Search – Wipro
     
     

108. Sudoku Solver – TCS
     
     

109. N-Queens – Capgemini
     
     

110. Palindrome Partitioning – Cognizant
     
     

111. Permutations II – Infosys
     
     

112. Combination Sum II – Wipro
     
     

113. Subsets II – TCS
     
     

114. Restore IP Addresses – Capgemini
     
     

115. Expression Add Operators – Cognizant
     
     

🔹 Stack & Queue (15 Questions)

116. Valid Parentheses – TCS
     
     

117. Min Stack – Wipro
     
     

118. Evaluate Reverse Polish Notation – Infosys
     
     

119. Implement Queue using Stacks – Capgemini
     
     

120. Implement Stack using Queues – Cognizant
     
     

121. Daily Temperatures – Infosys
     
     

122. Next Greater Element I – Wipro
     
     

123. Next Greater Element II – TCS
     
     

124. Remove All Adjacent Duplicates In String II – Capgemini
     
     

125. Design Circular Queue – Cognizant
     
     

126. Sliding Window Maximum – Infosys
     
     

127. Decode String – Wipro
     
     

128. Design Stack With Increment Operation – TCS
     
     

129. Number of Recent Calls – Capgemini
     
     

130. Simplify Path – Cognizant
     
     

🔹 Graphs (15 Questions)

131. Number of Islands – TCS
     
     

132. Clone Graph – Infosys
     
     

133. Course Schedule – Wipro
     
     

134. Course Schedule II – Capgemini
     
     

135. Graph Valid Tree – Cognizant
     
     

136. Pacific Atlantic Water Flow – Infosys
     
     

137. Redundant Connection – Wipro
     
     

138. Network Delay Time – TCS
     
     

139. Is Graph Bipartite? – Capgemini
     
     

140. Word Ladder – Cognizant
     
     

141. Reconstruct Itinerary – Infosys
     
     

142. Find the Town Judge – Wipro
     
     

143. All Paths From Source to Target – TCS
     
     

144. Minimum Height Trees – Capgemini
     
     

145. Critical Connections in a Network – Cognizant
     
     

🔹 Dynamic Programming (15 Questions)

146. Climbing Stairs – TCS
     
     

147. House Robber – Infosys
     
     

148. House Robber II – Wipro
     
     

149. Longest Palindromic Subsequence – Capgemini
     
     

150. Decode Ways – Cognizant
     
     

151. Maximum Subarray – Infosys
     
     

152. Partition Equal Subset Sum – Wipro
     
     

153. Coin Change – TCS
     
     

154. Longest Increasing Subsequence – Capgemini
     
     

155. Edit Distance – Cognizant
     
     

156. Interleaving String – Infosys
     
     

157. Target Sum – Wipro
     
     

158. Best Time to Buy and Sell Stock with Cooldown – TCS
     
     

159. Distinct Subsequences – Capgemini
     
     

160. Word Break – Cognizant
     
     

🔹 Bit Manipulation (10 Questions)

161. Single Number – Infosys
     
     

162. Number of 1 Bits – Wipro
     
     

163. Counting Bits – TCS
     
     

164. Missing Number – Capgemini
     
     

165. Sum of Two Integers – Cognizant
     
     

166. Reverse Bits – Infosys
     
     

167. Power of Two – Wipro
     
     

168. Hamming Distance – TCS
     
     

169. Bitwise AND of Numbers Range – Capgemini
     
     

170. Binary Watch – Cognizant
     
     

🔹 Interview Must-Solve (30 Questions)

171. LRU Cache – TCS
     
     

172. Median of Two Sorted Arrays – Infosys
     
     

173. Merge Intervals – Wipro
     
     

174. Trapping Rain Water – Capgemini
     
     

175. Longest Consecutive Sequence – Cognizant
     
     

176. Word Ladder II – Infosys
     
     

177. Basic Calculator – Wipro
     
     

178. Largest Rectangle in Histogram – TCS
     
     

179. Sliding Window Maximum – Capgemini
     
     

180. Regular Expression Matching – Cognizant
     
     

181. Wildcard Matching – Infosys
     
     

182. Minimum Window Substring – Wipro
     
     

183. Find Median from Data Stream – TCS
     
     

184. Palindrome Pairs – Capgemini
     
     

185. Design Add and Search Words Data Structure – Cognizant
     
     

186. LFU Cache – Infosys
     
     

187. Data Stream as Disjoint Intervals – Wipro
     
     

188. Count of Smaller Numbers After Self – TCS
     
     

189. Find Peak Element – Capgemini
     
     

190. Basic Calculator II – Cognizant
     
     

191. Insert Delete GetRandom O(1) – Infosys
     
     

192. Maximal Rectangle – Wipro
     
     

193. Read N Characters Given Read4 – TCS
     
     

194. Binary Tree Cameras – Capgemini
     
     

195. Paint House – Cognizant
     
     

196. Serialize and Deserialize BST – Infosys
     
     

197. Number of Digit One – Wipro
     
     

198. Dungeon Game – TCS
     
     

199. Burst Balloons – Capgemini
     
     

200. Minimum Number of Refueling Stops – Cognizant