250+ Coding Interview Questions Asked in Service-Based Companies (with Company Tags & Links)

1. Reverse a string – Asked in: Infosys
   
   

2. Check if a string is a palindrome – Asked in: Capgemini
   
   

3. Find the factorial of a number – Asked in: Wipro
   
   

4. Find the largest number in an array – Asked in: TCS
   
   

5. Find the smallest number in an array – Asked in: Cognizant
   
   

6. Calculate the sum of array elements – Asked in: Infosys
   
   

7. Count even and odd numbers in an array – Asked in: Accenture
   
   

8. Count vowels and consonants in a string – Asked in: IBM
   
   

9. Swap two numbers – Asked in: TCS
   
   

10. Print Fibonacci series – Asked in: Infosys
    
    

11. Check if a number is prime – Asked in: Wipro
    
    

12. Find GCD of two numbers – Asked in: TCS
    
    

13. Find LCM of two numbers – Asked in: Infosys
    
    

14. Check Armstrong number – Asked in: Capgemini
    
    

15. Check Perfect number – Asked in: Cognizant
    
    

16. Reverse a number – Asked in: IBM
    
    

17. Count digits in a number – Asked in: Accenture
    
    

18. Print prime numbers in a range – Asked in: TCS
    
    

19. Print multiplication table – Asked in: Infosys
    
    

20. Find power of a number – Asked in: Wipro
    
    

21. Convert binary to decimal – Asked in: Capgemini
    
    

22. Convert decimal to binary – Asked in: Cognizant
    
    

23. Remove duplicates from an array – Asked in: Infosys
    
    

24. Find frequency of elements in an array – Asked in: Accenture
    
    

25. Sort array using bubble sort – Asked in: TCS
    
    

26. Sort array using selection sort – Asked in: Wipro
    
    

27. Find second largest element – Asked in: IBM
    
    

28. Find second smallest element – Asked in: Capgemini
    
    

29. Merge two arrays – Asked in: Infosys
    
    

30. Find missing number in array (1 to N) – Asked in: TCS
    
    

31. Count occurrences of a character in string – Asked in: Wipro
    
    

32. Capitalize first letter of each word in string – Asked in: Accenture
    
    

33. Remove all white spaces from string – Asked in: Infosys
    
    

34. Replace character in string – Asked in: Cognizant
    
    

35. Remove special characters from string – Asked in: TCS
    
    

36. Compare two strings – Asked in: Wipro
    
    

37. Find length of string without using length() – Asked in: Capgemini
    
    

38. Convert lowercase to uppercase – Asked in: Infosys
    
    

39. Convert string to integer – Asked in: IBM
    
    

40. Convert integer to string – Asked in: Accenture
    
    

41. Find ASCII value of character – Asked in: TCS
    
    

42. Check if strings are anagrams – Asked in: Capgemini
    
    

43. Count number of words in string – Asked in: Infosys
    
    

44. Remove duplicates from string – Asked in: Wipro
    
    

45. Check if array is sorted – Asked in: Cognizant
    
    

46. Implement linear search – Asked in: TCS
    
    

47. Implement binary search – Asked in: Infosys
    
    

48. Find intersection of two arrays – Asked in: Wipro
    
    

49. Find union of two arrays – Asked in: Accenture
    
    

50. Find sum of digits of number – Asked in: Capgemini

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51. Find common elements in three sorted arrays – Asked in: Infosys
    
    

52. Check for pair with given sum in array – Asked in: Capgemini
    
    

53. Find majority element in array – Asked in: TCS
    
    

54. Kadane’s Algorithm – Max subarray sum – Asked in: Wipro
    
    

55. Check if array contains duplicate – Asked in: Infosys
    
    

56. Check if two strings are isomorphic – Asked in: IBM
    
    

57. Longest common prefix – Asked in: Accenture
    
    

58. Longest substring without repeating characters – Asked in: TCS
    
    

59. Group anagrams – Asked in: Wipro
    
    

60. Check if linked list is palindrome – Asked in: Infosys
    
    

61. Find middle of linked list – Asked in: Capgemini
    
    

62. Detect loop in linked list – Asked in: TCS
    
    

63. Remove Nth node from end – Asked in: Cognizant
    
    

64. Merge two sorted linked lists – Asked in: Wipro
    
    

65. Reverse a linked list – Asked in: Infosys
    
    

66. Find intersection of two linked lists – Asked in: Accenture
    
    

67. Add two numbers as linked list – Asked in: IBM
    
    

68. Remove duplicates from sorted list – Asked in: Capgemini
    
    

69. Delete node in a linked list – Asked in: TCS
    
    

70. Odd even linked list – Asked in: Wipro
    
    

71. Detect and remove loop in linked list – Asked in: Infosys
    
    

72. Implement stack using arrays – Asked in: Capgemini
    
    

73. Implement queue using arrays – Asked in: TCS
    
    

74. Implement circular queue – Asked in: Cognizant
    
    

75. Infix to postfix conversion – Asked in: Wipro
    
    

76. Evaluate postfix expression – Asked in: Infosys
    
    

77. Next greater element – Asked in: Accenture
    
    

78. Balanced parentheses – Asked in: IBM
    
    

79. Stock span problem – Asked in: Capgemini
    
    

80. LRU Cache implementation – Asked in: TCS
    
    

81. Insert interval – Asked in: Wipro
    
    

82. Merge intervals – Asked in: Infosys
    
    

83. Minimum platforms required – Asked in: Capgemini
    
    

84. Job scheduling problem – Asked in: TCS
    
    

85. N meeting in one room – Asked in: Wipro
    
    

86. Activity selection problem – Asked in: Infosys
    
    

87. Fractional knapsack problem – Asked in: IBM
    
    

88. 0/1 Knapsack problem – Asked in: Accenture
    
    

89. Longest common subsequence – Asked in: TCS
    
    

90. Longest palindromic subsequence – Asked in: Capgemini
    
    

91. Coin change problem – Asked in: Infosys
    
    

92. Rod cutting problem – Asked in: Cognizant
    
    

93. Minimum number of coins – Asked in: Accenture
    
    

94. Subset sum problem – Asked in: Wipro
    
    

95. Word break problem – Asked in: IBM
    
    

96. Longest increasing subsequence – Asked in: TCS
    
    

97. Maximum product subarray – Asked in: Infosys
    
    

98. Edit distance – Asked in: Capgemini
    
    

99. Boolean parenthesization problem – Asked in: Wipro
    
    

100. Palindrome partitioning – Asked in: TCS
     
     

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101. Two Sum Problem – Asked in: TCS
     
     

102. Move zeros to end of array – Asked in: Wipro
     
     

103. Rotate array by K elements – Asked in: Infosys
     
     

104. Check if subarray with 0 sum exists – Asked in: Capgemini
     
     

105. Find longest subarray with given sum – Asked in: Cognizant
     
     

106. Maximum sum increasing subsequence – Asked in: Infosys
     
     

107. Trapping Rain Water – Asked in: TCS
     
     

108. Minimum jumps to reach end – Asked in: Wipro
     
     

109. Chocolate Distribution Problem – Asked in: Capgemini
     
     

110. Activity Selection (Greedy) – Asked in: Accenture
     
     

111. Find missing and repeating number – Asked in: TCS
     
     

112. Find duplicate number (Floyd's Cycle) – Asked in: Infosys
     
     

113. Set Matrix Zeroes – Asked in: Wipro
     
     

114. Spiral Matrix – Asked in: Capgemini
     
     

115. Search in a sorted 2D matrix – Asked in: IBM
     
     

116. Find peak element – Asked in: Accenture
     
     

117. Kth smallest element in array – Asked in: TCS
     
     

118. Kth largest element using heap – Asked in: Infosys
     
     

119. Sliding window maximum – Asked in: Wipro
     
     

120. First negative integer in window – Asked in: Capgemini
     
     

121. Check if brackets are balanced – Asked in: Infosys
     
     

122. Implement queue using stack – Asked in: IBM
     
     

123. Implement stack using queue – Asked in: Accenture
     
     

124. LRU Cache – Asked in: Capgemini
     
     

125. LFU Cache – Asked in: Wipro
     
     

126. Flatten a linked list – Asked in: TCS
     
     

127. Clone a linked list with random pointer – Asked in: Infosys
     
     

128. Sort a stack – Asked in: Capgemini
     
     

129. Delete middle of a stack – Asked in: Wipro
     
     

130. Insert at bottom of stack – Asked in: TCS
     
     

131. Check for balanced tree – Asked in: Infosys
     
     

132. Diameter of binary tree – Asked in: Capgemini
     
     

133. Invert binary tree – Asked in: IBM
     
     

134. Zigzag traversal of binary tree – Asked in: Accenture
     
     

135. Boundary traversal of binary tree – Asked in: TCS
     
     

136. Top view of binary tree – Asked in: Infosys
     
     

137. Bottom view of binary tree – Asked in: Capgemini
     
     

138. Vertical order traversal – Asked in: Wipro
     
     

139. Symmetric tree – Asked in: Infosys
     
     

140. Binary tree from inorder & preorder – Asked in: IBM
     
     

141. Lowest common ancestor in binary tree – Asked in: Capgemini
     
     

142. Max depth of binary tree – Asked in: TCS
     
     

143. Sum root to leaf numbers – Asked in: Infosys
     
     

144. Path sum – Asked in: Wipro
     
     

145. Binary tree level order traversal – Asked in: Accenture
     
     

146. Convert binary tree to doubly linked list – Asked in: Capgemini
     
     

147. Serialize and deserialize binary tree – Asked in: Infosys
     
     

148. Check subtree of another tree – Asked in: TCS
     
     

149. Construct tree from postorder and inorder – Asked in: Capgemini
     
     

150. Flatten binary tree to linked list – Asked in: Wipro
     
     

151. Find all duplicates in array – Asked in: Infosys
     
     

152. Find first and last position of element – Asked in: TCS
     
     

153. Count number of subarrays with sum k – Asked in: Capgemini
     
     

154. Find pivot index – Asked in: Cognizant
     
     

155. Max consecutive ones – Asked in: Wipro
     
     

156. Missing number – Asked in: Accenture
     
     

157. Min size subarray sum – Asked in: Infosys
     
     

158. Find all numbers disappeared – Asked in: TCS
     
     

159. Minimum operations to make array equal – Asked in: IBM
     
     

160. Merge two sorted arrays – Asked in: Capgemini
     
     

161. Check array is sorted and rotated – Asked in: Wipro
     
     

162. Best time to buy and sell stock – Asked in: Infosys
     
     

163. Subarray product less than k – Asked in: Accenture
     
     

164. Find target indices after sorting – Asked in: TCS
     
     

165. Rearrange array elements by sign – Asked in: Wipro
     
     

166. Maximum average subarray I – Asked in: Capgemini
     
     

167. Find kth positive missing number – Asked in: Infosys
     
     

168. Number of good pairs – Asked in: Cognizant
     
     

169. Intersection of two arrays – Asked in: IBM
     
     

170. Relative sort array – Asked in: Capgemini
     
     

171. Check if number is power of two – Asked in: Wipro
     
     

172. Single number – Asked in: TCS
     
     

173. Hamming weight – Asked in: Infosys
     
     

174. Count set bits – Asked in: Accenture
     
     

175. Find XOR of numbers from 1 to n – Asked in: IBM
     
     

176. Sum of two integers without + - – Asked in: Capgemini
     
     

177. Reverse bits – Asked in: Wipro
     
     

178. Add binary – Asked in: Infosys
     
     

179. Bitwise AND of numbers range – Asked in: TCS
     
     

180. Find missing number using XOR – Asked in: Accenture
     
     

181. Subsets – Asked in: Wipro
     
     

182. Permutations – Asked in: Infosys
     
     

183. Combination sum – Asked in: Capgemini
     
     

184. Word search – Asked in: TCS
     
     

185. N queens – Asked in: IBM
     
     

186. Palindrome partitioning – Asked in: Accenture
     
     

187. Letter case permutation – Asked in: Cognizant
     
     

188. Generate parentheses – Asked in: Infosys
     
     

189. Sudoku solver – Asked in: Wipro
     
     

190. Restore IP addresses – Asked in: TCS
     
     

191. Gray code – Asked in: Capgemini
     
     

192. Combination sum II – Asked in: Infosys
     
     

193. Combinations – Asked in: Wipro
     
     

194. Subsets II – Asked in: Accenture
     
     

195. Path sum II – Asked in: TCS
     
     

196. Letter combinations of a phone number – Asked in: Capgemini
     
     

197. Permutations II – Asked in: Infosys
     
     

198. Word break – Asked in: Wipro
     
     

199. Palindrome partitioning II – Asked in: IBM
     
     

200. Minimum number of swaps to make string balanced – Asked in: Cognizant
     
     

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201. Validate Binary Search Tree – Asked in: Infosys
     
     

202. Lowest Common Ancestor of a BST – Asked in: Wipro
     
     

203. Binary Tree Inorder Traversal – Asked in: TCS
     
     

204. Construct Binary Tree from Inorder and Preorder – Asked in: Capgemini
     
     

205. Populating Next Right Pointers – Asked in: IBM
     
     

206. Flatten a Multilevel Doubly Linked List – Asked in: Infosys
     
     

207. Insert into a Binary Search Tree – Asked in: Cognizant
     
     

208. Sum of Left Leaves – Asked in: Wipro
     
     

209. Maximum Depth of N-ary Tree – Asked in: Accenture
     
     

210. Convert Sorted Array to BST – Asked in: TCS
     
     

211. Construct String from Binary Tree – Asked in: Infosys
     
     

212. Average of Levels in Binary Tree – Asked in: Capgemini
     
     

213. Binary Tree Tilt – Asked in: Wipro
     
     

214. Path Sum III – Asked in: Cognizant
     
     

215. Find Duplicate Subtrees – Asked in: Accenture
     
     

216. Construct Binary Tree from String – Asked in: IBM
     
     

217. Binary Tree Cameras – Asked in: TCS
     
     

218. Binary Tree Coloring Game – Asked in: Infosys
     
     

219. All Nodes Distance K in Binary Tree – Asked in: Capgemini
     
     

220. Recover Binary Search Tree – Asked in: Wipro
     
     

221. Boundary of Binary Tree – Asked in: Cognizant
     
     

222. Binary Tree Right Side View – Asked in: Infosys
     
     

223. Same Tree – Asked in: Capgemini
     
     

224. Count Complete Tree Nodes – Asked in: TCS
     
     

225. Binary Tree Paths – Asked in: IBM
     
     

226. Sum of Nodes with Even-Valued Grandparent – Asked in: Accenture
     
     

227. Longest ZigZag Path in Binary Tree – Asked in: Wipro
     
     

228. Tree Diameter – Asked in: Infosys
     
     

229. Count Good Nodes in Binary Tree – Asked in: Capgemini
     
     

230. Binary Search Tree Iterator – Asked in: Cognizant
     
     

231. Serialize and Deserialize BST – Asked in: IBM
     
     

232. Delete Node in a BST – Asked in: Wipro
     
     

233. Kth Smallest Element in BST – Asked in: Infosys
     
     

234. Validate Stack Sequences – Asked in: Capgemini
     
     

235. Check Completeness of a Binary Tree – Asked in: TCS
     
     

236. Maximum Width of Binary Tree – Asked in: Accenture
     
     

237. Find Largest Value in Each Tree Row – Asked in: Wipro
     
     

238. Cousins in Binary Tree – Asked in: Infosys
     
     

239. Vertical Order Traversal – Asked in: Cognizant
     
     

240. Binary Tree Postorder Traversal – Asked in: Capgemini
     
     

241. Sum of Root To Leaf Binary Numbers – Asked in: Wipro
     
     

242. Delete Leaves with a Given Value – Asked in: Infosys
     
     

243. Longest Univalue Path – Asked in: TCS
     
     

244. Find Bottom Left Tree Value – Asked in: IBM
     
     

245. Flip Equivalent Binary Trees – Asked in: Accenture
     
     

246. All Elements in Two BSTs – Asked in: Cognizant
     
     

247. Merge Two Binary Trees – Asked in: Capgemini
     
     

248. Binary Tree Level Order Traversal II – Asked in: Wipro
     
     

249. Path In Zigzag Labelled Binary Tree – Asked in: Infosys
     
     

250. Sum of Distances in Tree – Asked in: TCS