[ 110% Placement ] Coding Questions For Placement With Solution | Tech With Code

 Here are 400+ competitive questions with a solution. If you solve all these questions then we will guaranty you that you can crack any company. 

Topic:- Array

  1. Reverse the array
  2. Find the maximum and minimum element in an array
  3. Find the "Kth" max and min element of an array 
  4. Given an array which consists of only 0, 1 and 2. Sort the array without using any sorting algo
  5. Move all the negative elements to one side of the array 
  6. Find the Union and Intersection of the two sorted arrays.
  7. Write a program to cyclically rotate an array by one.
  8. find Largest sum contiguous Subarray [V. IMP]
  9. Minimise the maximum difference between heights [V.IMP]
  10. Minimum no. of Jumps to reach end of an array
  11. find duplicate in an array of N+1 Integers
  12. Merge 2 sorted arrays without using Extra space.
  13. Kadane's Algo [V.V.V.V.V IMP]
  14. Merge Intervals
  15. Next Permutation
  16. Count Inversion
  17. Best time to buy and Sell stock
  18. find all pairs on integer array whose sum is equal to given number
  19. find common elements In 3 sorted arrays
  20. Rearrange the array in alternating positive and negative items with O(1) extra space
  21. Find if there is any subarray with sum equal to 0
  22. Find factorial of a large number
  23. find maximum product subarray 
  24. Find longest coinsecutive subsequence
  25. Given an array of size n and a number k, fin all elements that appear more than " n/k " times.
  26. Maximum profit by buying and selling a share atmost twice
  27. Find whether an array is a subset of another array
  28. Find the triplet that sum to a given value
  29. Trapping Rain water problem
  30. Chocolate Distribution problem
  31. Smallest Subarray with sum greater than a given value
  32. Three way partitioning of an array around a given value
  33. Minimum swaps required bring elements less equal K together
  34. Minimum no. of operations required to make an array palindrome
  35. Median of 2 sorted arrays of equal size
  36. Median of 2 sorted arrays of different size
  37. Spiral traversal on a Matrix

  38. Search an element in a matriix

  39. Find median in a row wise sorted matrix

  40. Find row with maximum no. of 1's

  41. Print elements in sorted order using row-column wise sorted matrix

  42. Maximum size rectangle

  43. Find a specific pair in matrix

  44. Rotate matrix by 90 degrees

  45. Kth smallest element in a row-cpumn wise sorted matrix

  46. Common elements in all rows of a given matrix





  47. Reverse a String

  48. Check whether a String is Palindrome or not

  49. Find Duplicate characters in a string

  50. Why strings are immutable in Java?

  51. Write a Code to check whether one string is a rotation of another

  52. Write a Program to check whether a string is a valid shuffle of two strings or not

  53. Count and Say problem

  54. Write a program to find the longest Palindrome in a string.[ Longest palindromic Substring]

  55. Find Longest Recurring Subsequence in String

  56. Print all Subsequences of a string.

  57. Print all the permutations of the given string

  58. Split the Binary string into two substring with equal 0’s and 1’s

  59. Word Wrap Problem [VERY IMP].

  60. EDIT Distance [Very Imp]

  61. Find next greater number with same set of digits. [Very Very IMP]

  62. Balanced Parenthesis problem.[Imp]

  63. Word break Problem[ Very Imp]

  64. Rabin Karp Algo

  65. KMP Algo

  66. Convert a Sentence into its equivalent mobile numeric keypad sequence.

  67. Minimum number of bracket reversals needed to make an expression balanced.

  68. Count All Palindromic Subsequence in a given String.

  69. Count of number of given string in 2D character array

  70. Search a Word in a 2D Grid of characters.

  71. Boyer Moore Algorithm for Pattern Searching.

  72. Converting Roman Numerals to Decimal

  73. Longest Common Prefix

  74. Number of flips to make binary string alternate

  75. Find the first repeated word in string.

  76. Minimum number of swaps for bracket balancing.

  77. Find the longest common subsequence between two strings.

  78. Program to generate all possible valid IP addresses from given  string.

  79. Write a program tofind the smallest window that contains all characters of string itself.

  80. Rearrange characters in a string such that no two adjacent are same

  81. Minimum characters to be added at front to make string palindrome

  82. Given a sequence of words, print all anagrams together

  83. Find the smallest window in a string containing all characters of another string

  84. Recursively remove all adjacent duplicates

  85. String matching where one string contains wildcard characters

  86. Function to find Number of customers who could not get a computer

  87. Transform One String to Another using Minimum Number of Given Operation

  88. Check if two given strings are isomorphic to each other

  89. Recursively print all sentences that can be formed from list of word lists





  90. Find first and last positions of an element in a sorted array

  91. Find a Fixed Point (Value equal to index) in a given array

  92. Search in a rotated sorted array

  93. square root of an integer

  94. Maximum and minimum of an array using minimum number of comparisons

  95. Optimum location of point to minimize total distance

  96. Find the repeating and the missing

  97. find majority element

  98. Searching in an array where adjacent differ by at most k

  99. find a pair with a given difference

  100. find four elements that sum to a given value

  101. maximum sum such that no 2 elements are adjacent

  102. Count triplet with sum smaller than a given value

  103. merge 2 sorted arrays

  104. print all subarrays with 0 sum

  105. Product array Puzzle

  106. Sort array according to count of set bits

  107. minimum no. of swaps required to sort the array

  108. Bishu and Soldiers

  109. Rasta and Kheshtak

  110. Kth smallest number again

  111. Find pivot element in a sorted array

  112. K-th Element of Two Sorted Arrays

  113. Aggressive cows

  114. Book Allocation Problem

  115. EKOSPOJ:

  116. Job Scheduling Algo

  117. Missing Number in AP

  118. Smallest number with atleastn trailing zeroes infactorial

  119. Painters Partition Problem:

  120. ROTI-Prata SPOJ

  121. DoubleHelix SPOJ

  122. Subset Sums

  123. Findthe inversion count

  124. Implement Merge-sort in-place

  125. Partitioning and Sorting Arrays with Many Repeated Entries





  126. Write a Program to reverse the Linked List. (Both Iterative and recursive)

  127. Reverse a Linked List in group of Given Size. [Very Imp]

  128. Write a program to Detect loop in a linked list.

  129. Write a program to Delete loop in a linked list.

  130. Find the starting point of the loop. 

  131. Remove Duplicates in a sorted Linked List.

  132. Remove Duplicates in a Un-sorted Linked List.

  133. Write a Program to Move the last element to Front in a Linked List.

  134. Add “1” to a number represented as a Linked List.

  135. Add two numbers represented by linked lists.

  136. Intersection of two Sorted Linked List.

  137. Intersection Point of two Linked Lists.

  138. Merge Sort For Linked lists.[Very Important]

  139. Quicksort for Linked Lists.[Very Important]

  140. Find the middle Element of a linked list.

  141. Check if a linked list is a circular linked list.

  142. Split a Circular linked list into two halves.

  143. Write a Program to check whether the Singly Linked list is a palindrome or not.

  144. Deletion from a Circular Linked List.

  145. Reverse a Doubly Linked list.

  146. Find pairs with a given sum in a DLL.

  147. Count triplets in a sorted DLL whose sum is equal to given value “X”.

  148. Sort a “k”sorted Doubly Linked list.[Very IMP]

  149. Rotate DoublyLinked list by N nodes.

  150. Rotate a Doubly Linked list in group of Given Size.[Very IMP]

  151. Can we reverse a linked list in less than O(n) ?

  152. Why Quicksort is preferred for. Arrays and Merge Sort for LinkedLists ?

  153. Flatten a Linked List

  154. Sort a LL of 0's, 1's and 2's

  155. Clone a linked list with next and random pointer

  156. Merge K sorted Linked list

  157. Multiply 2 no. represented by LL

  158. Delete nodes which have a greater value on right side

  159. Segregate even and odd nodes in a Linked List

  160. Program for n’th node from the end of a Linked List

  161. Find the first non-repeating character from a stream of characters





  162. level order traversal

  163. Reverse Level Order traversal

  164. Height of a tree

  165. Diameter of a tree

  166. Mirror of a tree

  167. Inorder Traversal of a tree both using recursion and Iteration

  168. Preorder Traversal of a tree both using recursion and Iteration

  169. Postorder Traversal of a tree both using recursion and Iteration

  170. Left View of a tree

  171. Right View of Tree

  172. Top View of a tree

  173. Bottom View of a tree

  174. Zig-Zag traversal of a binary tree

  175. Check if a tree is balanced or not

  176. Diagnol Traversal of a Binary tree

  177. Boundary traversal of a Binary tree

  178. Construct Binary Tree from String with Bracket Representation

  179. Convert Binary tree into Doubly Linked List

  180. Convert Binary tree into Sum tree

  181. Construct Binary tree from Inorder and preorder traversal

  182. Find minimum swaps required to convert a Binary tree into BST

  183. Check if Binary tree is Sum tree or not

  184. Check if all leaf nodes are at same level or not

  185. Check if a Binary Tree contains duplicate subtrees of size 2 or more [ IMP ]

  186. Check if 2 trees are mirror or not

  187. Sum of Nodes on the Longest path from root to leaf node 

  188. Check if given graph is tree or not.  [ IMP ]

  189. Find Largest subtree sum in a tree

  190. Maximum Sum of nodes in Binary tree such that no two are adjacent 

  191. Print all "K" Sum paths in a Binary tree

  192. Find LCA in a Binary tree

  193. Find distance between 2 nodes in a Binary tree

  194. Kth Ancestor of node in a Binary tree

  195. Find all Duplicate subtrees in a Binary tree [ IMP ]

  196. Tree Isomorphism Problem





  197. Fina a value in a BST

  198. Deletion of a node in a BST

  199. Find min and max value in a BST

  200. Find inorder successor and inorder predecessor in a BST

  201. Check if a tree is a BST or not 

  202. Populate Inorder successor of all nodes

  203. Find LCA  of 2 nodes in a BST

  204. Construct BST from preorder traversal

  205. Convert Binary tree into BST

  206. Convert a normal BST into a Balanced BST

  207. Merge two BST [ V.V.V>IMP ]

  208. Find Kth largest element in a BST

  209. Find Kth smallest element in a BST

  210. Count pairs from 2 BST whose sum is equal to given value "X"

  211. Find the median of BST in O(n) time and O(1) space

  212. Count BST ndoes that lie in a given range

  213. Replace every element with the least greater element on its right

  214. Given "n" appointments, find the conflicting appointments

  215. Check preorder is valid or not

  216. Check whether BST contains Dead end

  217. Largest BST in a Binary Tree [ V.V.V.V.V IMP ]

  218. Flatten BST to sorted list





  219. Activity Selection Problem

  220. Job SequencingProblem

  221. Huffman Coding

  222. Water Connection Problem

  223. Fractional Knapsack Problem

  224. Greedy Algorithm to find Minimum number of Coins

  225. Maximum trains for which stoppage can be provided

  226. Minimum Platforms Problem

  227. Buy Maximum Stocks if i stocks can be bought on i-th day

  228. Find the minimum and maximum amount to buy all N candies

  229. Minimize Cash Flow among a given set of friends who have borrowed money from each other

  230. Minimum Cost to cut a board into squares

  231. Check if it is possible to survive on Island

  232. Find maximum meetings in one room

  233. Maximum product subset of an array

  234. Maximize array sum after K negations

  235. Maximize the sum of arr[i]*i

  236. Maximum sum of absolute difference of an array

  237. Maximize sum of consecutive differences in a circular array

  238. Minimum sum of absolute difference of pairs of two arrays

  239. Program for Shortest Job First (or SJF) CPU Scheduling

  240. Program for Least Recently Used (LRU) Page Replacement algorithm

  241. Smallest subset with sum greater than all other elements

  242. Chocolate Distribution Problem

  243. DEFKIN -Defense of a Kingdom

  244. DIEHARD -DIE HARD

  245. GERGOVIA -Wine trading in Gergovia

  246. Picking Up Chicks

  247. CHOCOLA –Chocolate

  248. ARRANGE -Arranging Amplifiers

  249. K Centers Problem

  250. Minimum Cost of ropes

  251. Find smallest number with given number of digits and sum of digits

  252. Rearrange characters in a string such that no two adjacent are same

  253. Find maximum sum possible equal sum of three stacks





  254. Rat in a maze Problem

  255. Printing all solutions in N-Queen Problem

  256. Word Break Problem using Backtracking

  257. Remove Invalid Parentheses

  258. Sudoku Solver

  259. m Coloring Problem

  260. Print all palindromic partitions of a string

  261. Subset Sum Problem

  262. The Knight’s tour problem

  263. Tug of War

  264. Find shortest safe route in a path with landmines

  265. Combinational Sum

  266. Find Maximum number possible by doing at-most K swaps

  267. Print all permutations of a string 

  268. Find if there is a path of more than k length from a source

  269. Longest Possible Route in a Matrix with Hurdles

  270. Print all possible paths from top left to bottom right of a mXn matrix

  271. Partition of a set intoK subsets with equal sum

  272. Find the K-th Permutation Sequence of first N natural numbers





  273.  Implement Stack from Scratch

  274.  Implement Queue from Scratch

  275. Implement 2 stack in an array

  276. find the middle element of a stack

  277. Implement "N" stacks in an Array

  278. Check the expression has valid or Balanced parenthesis or not.

  279. Reverse a String using Stack

  280. Design a Stack that supports getMin() in O(1) time and O(1) extra space.

  281. Find the next Greater element

  282. The celebrity Problem

  283. Arithmetic Expression evaluation

  284. Evaluation of Postfix expression

  285. Implement a method to insert an element at its bottom without using any other data structure.

  286. Reverse a stack using recursion

  287. Sort a Stack using recursion

  288. Merge Overlapping Intervals

  289. Largest rectangular Area in Histogram

  290. Length of the Longest Valid Substring

  291. Expression contains redundant bracket or not

  292. Implement Stack using Queue

  293. Implement Stack using Deque

  294. Stack Permutations (Check if an array is stack permutation of other)

  295. Implement Queue using Stack  

  296. Implement "n" queue in an array

  297. Implement a Circular queue

  298. LRU Cache Implementationa

  299. Reverse a Queue using recursion

  300. Reverse the first “K” elements of a queue

  301. Interleave the first half of the queue with second half

  302. Find the first circular tour that visits all Petrol Pumps

  303. Minimum time required to rot all oranges

  304. Distance of nearest cell having 1 in a binary matrix

  305. First negative integer in every window of size “k”

  306. Check if all levels of two trees are anagrams or not.

  307. Sum of minimum and maximum elements of all subarrays of size “k”.

  308. Minimum sum of squares of character counts in a given string after removing “k” characters.

  309. Queue based approach or first non-repeating character in a stream.

  310. Next Smaller Element





  311. Implement a Maxheap/MinHeap using arrays and recursion.

  312. Sort an Array using heap. (HeapSort)

  313. Maximum of all subarrays of size k.

  314. “k” largest element in an array

  315. Kth smallest and largest element in an unsorted array

  316. Merge “K” sorted arrays. [ IMP ]

  317. Merge 2 Binary Max Heaps

  318. Kth largest sum continuous subarrays

  319. Leetcode- reorganize strings

  320. Merge “K” Sorted Linked Lists [V.IMP]

  321. Smallest range in “K” Lists

  322. Median in a stream of Integers

  323. Check if a Binary Tree is Heap

  324. Connect “n” ropes with minimum cost

  325. Convert BST to Min Heap

  326. Convert min heap to max heap

  327. Rearrange characters in a string such that no two adjacent are same.

  328. Minimum sum of two numbers formed from digits of an array





  329. Create a Graph, print it

  330. Implement BFS algorithm 

  331. Implement DFS Algo 

  332. Detect Cycle in Directed Graph using BFS/DFS Algo 

  333. Detect Cycle in UnDirected Graph using BFS/DFS Algo 

  334. Search in a Maze

  335. Minimum Step by Knight

  336. flood fill algo

  337. Clone a graph

  338. Making wired Connections

  339. word Ladder 

  340. Dijkstra algo

  341. Implement Topological Sort 

  342. Minimum time taken by each job to be completed given by a Directed Acyclic Graph

  343. Find whether it is possible to finish all tasks or not from given dependencies

  344. Find the no. of Isalnds

  345. Given a sorted Dictionary of an Alien Language, find order of characters

  346. Implement Kruksal’sAlgorithm

  347. Implement Prim’s Algorithm

  348. Total no. of Spanning tree in a graph

  349. Implement Bellman Ford Algorithm

  350. Implement Floyd warshallAlgorithm

  351. Travelling Salesman Problem

  352. Graph ColouringProblem

  353. Snake and Ladders Problem

  354. Find bridge in a graph

  355. Count Strongly connected Components(Kosaraju Algo)

  356. Check whether a graph is Bipartite or Not

  357. Detect Negative cycle in a graph

  358. Longest path in a Directed Acyclic Graph

  359. Journey to the Moon

  360. Cheapest Flights Within K Stops

  361. Oliver and the Game

  362. Water Jug problem using BFS

  363. Water Jug problem using BFS

  364. Find if there is a path of more thank length from a source

  365. M-ColouringProblem

  366. Minimum edges to reverse o make path from source to destination

  367. Paths to travel each nodes using each edge(Seven Bridges)

  368. Vertex Cover Problem

  369. Chinese Postman or Route Inspection

  370. Number of Triangles in a Directed and Undirected Graph

  371. Minimise the cashflow among a given set of friends who have borrowed money from each other

  372. Two Clique Problem





  373. Construct a trie from scratch

  374. Find shortest unique prefix for every word in a given list

  375. Word Break Problem | (Trie solution)

  376. Given a sequence of words, print all anagrams together

  377. Implement a Phone Directory

  378. Print unique rows in a given boolean matrix





  379. Coin ChangeProblem

  380. Knapsack Problem

  381. Binomial CoefficientProblem

  382. Permutation CoefficientProblem

  383. Program for nth Catalan Number

  384. Matrix Chain Multiplication 

  385. Edit Distance

  386. Subset Sum Problem

  387. Friends Pairing Problem

  388. Gold Mine Problem

  389. Assembly Line SchedulingProblem

  390. Painting the Fenceproblem

  391. Maximize The Cut Segments

  392. Longest Common Subsequence

  393. Longest Repeated Subsequence

  394. Longest Increasing Subsequence

  395. Space Optimized Solution of LCS

  396. LCS (Longest Common Subsequence) of three strings

  397. Maximum Sum Increasing Subsequence

  398. Count all subsequences having product less than K

  399. Longest subsequence such that difference between adjacent is one

  400. Maximum subsequence sum such that no three are consecutive

  401. Egg Dropping Problem

  402. Maximum Length Chain of Pairs

  403. Maximum size square sub-matrix with all 1s

  404. Maximum sum of pairs with specific difference

  405. Min Cost PathProblem

  406. Maximum difference of zeros and ones in binary string

  407. Minimum number of jumps to reach end

  408. Minimum cost to fill given weight in a bag

  409. Minimum removals from array to make max –min <= K

  410. Longest Common Substring

  411. Count number of ways to reacha given score in a game

  412. Count Balanced Binary Trees of Height h

  413. LargestSum Contiguous Subarray [V>V>V>V IMP ]

  414. Smallest sum contiguous subarray

  415. Unbounded Knapsack (Repetition of items allowed)

  416. Word Break Problem

  417. Largest Independent Set Problem

  418. Partition problem

  419. Longest Palindromic Subsequence

  420. Count All Palindromic Subsequence in a given String

  421. Longest Palindromic Substring

  422. Longest alternating subsequence

  423. Weighted Job Scheduling

  424. Coin game winner where every player has three choices

  425. Count Derangements (Permutation such that no element appears in its original position) [ IMPORTANT ]

  426. Maximum profit by buying and selling a share at most twice [ IMP ]

  427. Optimal Strategy for a Game

  428. Optimal Binary Search Tree

  429. Palindrome PartitioningProblem

  430. Word Wrap Problem

  431. Mobile Numeric Keypad Problem [ IMP ]

  432. Boolean Parenthesization Problem

  433. Largest rectangular sub-matrix whose sum is 0

  434. Largest area rectangular sub-matrix with equal number of 1’s and 0’s [ IMP ]

  435. Maximum sum rectangle in a 2D matrix

  436. Maximum profit by buying and selling a share at most k times

  437. Find if a string is interleaved of two other strings

  438. Maximum Length of Pair Chain





  439. Count set bits in an integer

  440. Find the two non-repeating elements in an array of repeating elements

  441. Count number of bits to be flipped to convert A to B

  442. Count total set bits in all numbers from 1 to n

  443. Program to find whether a no is power of two

  444. Find position of the only set bit

  445. Copy set bits in a range

  446. Divide two integers without using multiplication, division and mod operator

  447. Calculate square of a number without using *, / and pow()

  448. Power Set


Many More Comming soon...

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