1. Count of strings that can be formed from another string using each character at-most once
  2. Initialize an ArrayList in Java
  3. Finding n-th term of series 3, 13, 42, 108, 235…
  4. Find n-th term of series 1, 4, 27, 16, 125, 36, 343 .......
  5. Delete all Prime Nodes from a Singly Linked List
  6. Implement a stack using singly linked list
  7. Delete all the even nodes from a Doubly Linked List
  8. Probability of rain on N+1th day
  9. Probability of a key K present in array
  10. Count pairs with Bitwise OR as Even number
  11. Count pairs with Bitwise AND as ODD number
  12. Count pairs with Bitwise XOR as ODD number
  13. Check if a key is present in every segment of size k in an array
  14. Delete array element in given index range [L - R]
  15. How to randomly select rows from Pandas DataFrame
  16. Find Nth term of the series 0, 2, 4, 8, 12, 18...
  17. Find Nth term of the series 5, 13, 25, 41, 61...
  18. Find Nth term of the series 3, 14, 39, 84...
  19. Find Nth term of the series 1, 8, 54, 384...
  20. Find Nth term of the series 1, 1, 2, 6, 24...
  21. Difference Between LinkedList and LinkedHashSet in Java
  22. Replace every element of the array by sum of all other elements
  23. Product of all prime nodes in a Doubly Linked List
  24. Convert a String to Integer Array in C/C++
  25. Sum of the nodes of a Singly Linked List
  26. Find count of common nodes in two Doubly Linked Lists
  27. Balance a string after removing extra brackets
  28. Delete all the nodes from the list which are less than K
  29. Convert List of Characters to String in Java
  30. Find other two sides and angles of a right angle triangle
  31. Delete linked list nodes which have a greater value on left side
  32. Delete all the nodes from a doubly linked list that are smaller than a given value
  33. Sum of all nodes in a doubly linked list divisible by a given number K
  34. Code valid in both C and C++ but produce different output
  35. Program to Convert List to Map in Java
  36. Delete all the nodes from the list which are divisible by any given number K
  37. Replace even nodes of a doubly linked list with the elements of array
  38. Delete linked list nodes which have a Lesser Value on Left Side
  39. Maximum element in min heap
  40. Sum of the nodes of a Circular Linked List
  41. Delete all the even nodes of a Circular Linked List
  42. Print all even nodes of Binary Search Tree
  43. Delete all Prime Nodes from a Circular Singly Linked List
  44. Print Sum and Product of all Non-Leaf nodes in Binary Tree
  45. Find normal at a given point on the curve
  46. Find first and last element of ArrayList in java
  47. Remove all elements from the ArrayList in Java
  48. Remove repeated elements from ArrayList in Java
  49. Find Tangent at a given point on the curve
  50. Convert String to Double in Java
  51. Program to Convert a Vector to List in Java
  52. Min and Max in a List in Java
  53. Convert Double to Integer in Java
  54. Find common elements in two ArrayLists in Java
  55. Convert an ArrayList of String to a String array in Java
  56. Difference between HashMap and HashSetv
  57. Find two non-overlapping pairs having equal sum in an Array
  58. Difference between length of Array and size of ArrayList in Java
  59. Print all nodes between two given levels in Binary Tree
  60. Method within method in java
  61. Split a list into two halves in Java
  62. Get name of current method being executed in Java
  63. How do Dynamic arrays work?
  64. Differences between wait() and join() methods in Java
  65. Count number of a class objects created in Java
  66. Get first and last elements from ArrayList in Java
  67. Difference between ArrayList and HashSet in Java
  68. What is the difference between field, variable, attribute, and property in Java
  69. LinkedHashMap and LinkedHashSet in Java
  70. Calculate volume and surface area of Torus
  71. Format Specifiers in Java
  72. Remove all occurrences of an element from Array in Java
  73. Future and FutureTask in java
  74. Find minimum and maximum elements in singly Circular Linked List
  75. BlockingQueue Interface in Java
  76. Difference Between Daemon Threads and User Threads In Java
  77. Deletion at different positions in a Circular Linked List
  78. Delete all odd or even positioned nodes from Circular Linked List
  79. Array implementation of queue (Simple)
  80. Sum and Product of the nodes of a Circular Singly Linked List which are divisible by K
  81. Difference between a Static Queue and a Singly Linked List
  82. Generate random String of given size in Java
  83. Print all pairs in an unsorted array with equal sum
  84. ArrayList vs. HashMap in Java
  85. How to select multiple columns in a pandas dataframe
  86. Non-generic Vs Generic Collection in Java
  87. DelayQueue class in Java with Example
  88. Different ways to sort an array in descending order in C#
  89. Randomly select items from a List in Java
  90. Find smallest and largest element from square matrix diagonals
  91. Reset Index in Pandas Dataframe
  92. Blocks in PL/SQL
  93. Get unique values from a column in Pandas DataFrame
  94. How to drop one or multiple columns in Pandas Dataframe
  95. valarray atan2() function in C++
  96. Difference and similarities between HashSet, LinkedHashSet and TreeSet in Java
  97. Maximum sum of cocktail glass in a 2D matrix
You may use GeeksforGeeks CONTRIBUTE portal to help other geeks. For more info, please refer this.

  1. Write a program to reverse digits of a number
  2. Write a function to delete a Linked List
  3. Reverse a linked list
  4. k largest(or smallest) elements in an array | added Min Heap method
  5. Compute the integer absolute value (abs) without branching
  6. Print reverse of a Linked List without actually reversing
  7. Count Inversions in an array | Set 1 (Using Merge Sort)
  8. Maximum and minimum of an array using minimum number of comparisons
  9. Maximum width of a binary tree
  10. Identical Linked Lists
  11. Find the two repeating elements in a given array
  12. Evaluation order of operands
  13. Check if a binary tree is subtree of another binary tree | Set 1
  14. Add two numbers represented by linked lists | Set 1
  15. Delete a given node in Linked List under given constraints
  16. Sorted Linked List to Balanced BST
  17. Check whether a given string is an interleaving of two other given strings
  18. Hamiltonian Cycle | Backtracking-6
  19. Longest Palindromic Subsequence | DP-12
  20. Find a triplet from three linked lists with sum equal to a given number
  21. Find a pair with given sum in a Balanced BST
  22. Minimum insertions to form a palindrome | DP-28
  23. Longest Common Substring | DP-29
  24. Delete N nodes after M nodes of a linked list
  25. Print all possible paths from top left to bottom right of a mXn matrix
  26. Pairwise swap elements of a given linked list by changing links
  27. Find if two rectangles overlap
  28. Check if a given Binary Tree is height balanced like a Red-Black Tree
  29. Remove minimum elements from either side such that 2*min becomes more than max
  30. Program for nth Catalan Number
  31. Check if a binary tree is subtree of another binary tree | Set 2
  32. Print squares of first n natural numbers without using *, / and -
  33. Multiply two polynomials
  34. How to check if two given sets are disjoint?
  35. K'th Smallest/Largest Element in Unsorted Array | Set 3 (Worst Case Linear Time)
  36. Given a linked list of line segments, remove middle points
  37. Longest Even Length Substring such that Sum of First and Second Half is same
  38. Print all paths from a given source to a destination
  39. Greedy Algorithm for Egyptian Fraction
  40. Check whether a binary tree is a complete tree or not | Set 2 (Recursive Solution)
  41. Group multiple occurrence of array elements ordered by first occurrence
  42. Iterative Merge Sort
  43. Compute n! under modulo p
  44. Converting Decimal Number lying between 1 to 3999 to Roman Numerals
  45. Remove spaces from a given string
  46. Compute sum of digits in all numbers from 1 to n
  47. Count BST subtrees that lie in given range
  48. Converting a Real Number (between 0 and 1) to Binary String
  49. Count distinct elements in every window of size k
  50. Collect maximum points in a grid using two traversals
  51. Maximum Path Sum in a Binary Tree
  52. Print string of odd length in 'X' format
  53. Lazy Propagation in Segment Tree
  54. Find minimum possible size of array with given rules for removing elements
  55. Count number of ways to partition a set into k subsets
  56. Compare two strings represented as linked lists
  57. Print cousins of a given node in Binary Tree
  58. Number of paths with exactly k coins
  59. Combinatorial Game Theory | Set 3 (Grundy Numbers/Nimbers and Mex)
  60. Clone a linked list with next and random pointer in O(1) space
  61. Find the smallest twins in given range
  62. Count number of ways to divide a number in 4 parts
  63. Print individual digits as words without using if or switch
  64. Euler's criterion (Check if square root under modulo p exists)
  65. Find Square Root under Modulo p | Set 1 (When p is in form of 4*i + 3)
  66. G-Fact 19 (Logical and Bitwise Not Operators on Boolean)
  67. Rearrange an array in maximum minimum form | Set 1
  68. Form minimum number from given sequence
  69. How to avoid overflow in modular multiplication?
  70. 1's and 2's complement of a Binary Number
  71. Number of Integral Points between Two Points
  72. Add 1 to a number represented as linked list
  73. Comparator Interface in Java with Examples
  74. Print root to leaf paths without using recursion
  75. Maximum product of a triplet (subsequnece of size 3) in array
  76. Find smallest range containing elements from k lists
  77. Find if string is K-Palindrome or not | Set 1
  78. Number of ways to calculate a target number using only array elements
  79. Longest Common Prefix using Character by Character Matching
  80. Longest Common Prefix using Trie
  81. Implement a stack using single queue
  82. Find if string is K-Palindrome or not | Set 2
  83. Reverse an array in groups of given size | Set 2 (Variations of Set 1 )
  84. Find if an expression has duplicate parenthesis or not
  85. Maximize value of (arr[i] - i) - (arr[j] - j) in an array
  86. Longest repeating and non-overlapping substring
  87. Pairs of complete strings in two sets of strings
  88. Connect Nodes at same Level (Level Order Traversal)
  89. Queries in a Matrix
  90. Count all pairs with given XOR
  91. Swap Nodes in Binary tree of every k'th level
  92. Count of distinct substrings of a string using Suffix Trie
  93. Check if there is a root to leaf path with given sequence
  94. Aliquot Sequence
  95. Sum of maximum elements of all subsets
  96. Count characters at same position as in English alphabet
  97. Maximum subsequence sum such that no three are consecutive
  98. Print matrix in diagonal pattern
  99. Maximum decimal value path in a binary matrix
  100. Sort even-placed elements in increasing and odd-placed in decreasing order
  101. Find the first natural number whose factorial is divisible by x
  102. Count natural numbers whose all permutation are greater than that number
  103. Rearrange an array to minimize sum of product of consecutive pair elements
  104. Find pair with greatest product in array
  105. Find a partition point in array
  106. Find pairs in array whose sums already exist in array
  107. K-th smallest element after removing some integers from natural numbers
  108. Queries on substring palindrome formation
  109. Sum of matrix in which each element is absolute difference of its row and column numbers
  110. Friends Pairing Problem
  111. Minimum steps to reach target by a Knight | Set 1
  112. Count binary strings with k times appearing adjacent two set bits
  113. Check if there exist two elements in an array whose sum is equal to the sum of rest of the array
  114. Check if reversing a sub array make the array sorted
  115. Maximize sum of N X N upper left sub-matrix from given 2N X 2N matrix
  116. Find all triplets with zero sum
  117. Print a matrix in alternate manner (left to right then right to left)
  118. Circular Singly Linked List | Insertion
  119. Largest subsequence having GCD greater than 1
  120. Number with maximum number of prime factors
  121. Ways to represent a number as a sum of 1's and 2's
  122. Make largest palindrome by changing at most K-digits
  123. Find largest word in dictionary by deleting some characters of given string
  124. Number Theory | Generators of finite cyclic group under addition
  125. Find longest sequence of 1's in binary representation with one flip
  126. Character replacement after removing duplicates from a string
  127. Lexicographically first palindromic string
  128. Minimum swaps to reach permuted array with at most 2 positions left swaps allowed
  129. Point Clipping Algorithm in Computer Graphics
  130. Convert decimal fraction to binary number
  131. Search, insert and delete in an unsorted array
  132. Search, insert and delete in a sorted array
  133. Find sum of non-repeating (distinct) elements in an array
  134. Count half nodes in a Binary tree (Iterative and Recursive)
  135. Noble integers in an array (count of greater elements is equal to value)
  136. Find Duplicates of array using bit array
  137. Multiply large integers under large modulo
  138. Change a Binary Tree so that every node stores sum of all nodes in left subtree
  139. Lexicographically minimum string rotation | Set 1
  140. Find the largest three elements in an array
  141. Triangular Numbers
  142. Program to print Sum Triangle for a given array
  143. Check if two numbers are equal without using arithmetic and comparison operators
  144. Queue | Set 2 (Linked List Implementation)
  145. Search an element in a Linked List (Iterative and Recursive)
  146. Insertion Sort for Singly Linked List
  147. Delete last occurrence of an item from linked list
  148. Move spaces to front of string in single traversal
  149. Binary representation of next number
  150. Sort an array of strings according to string lengths
  151. Binary representation of next greater number with same number of 1's and 0's
  152. Remove all occurrences of duplicates from a sorted Linked List
  153. k-th distinct (or non-repeating) element in an array.
  154. Count number of ways to jump to reach end
  155. Reverse an array without using subtract sign ‘-‘ anywhere in the code
  156. First element occurring k times in an array
  157. Partitioning a linked list around a given value and If we don't care about making the elements of the list "stable"
  158. Count subsets having distinct even numbers
  159. Smallest window that contains all characters of string itself
  160. Shortest Uncommon Subsequence
  161. Program to find Smallest and Largest Word in a String
  162. Program to remove vowels from a String
  163. Convert a given Binary tree to a tree that holds Logical AND property
  164. Sum of divisors of factorial of a number
  165. Check whether a given binary tree is perfect or not
  166. Find Index of 0 to be replaced with 1 to get longest continuous sequence of 1s in a binary array | Set-2
  167. Find uncommon characters of the two strings
  168. String containing first letter of every word in a given string with spaces
  169. URLify a given string (Replace spaces is %20)
  170. Maximizing Unique Pairs from two arrays
  171. Reverse vowels in a given string
  172. Program for quotient and remainder of big number
  173. Count pairs from two sorted arrays whose sum is equal to a given value x
  174. Painting Fence Algorithm
  175. Check if a string is Isogram or not
  176. Check if absolute difference of consecutive nodes is 1 in Linked List
  177. Check if an array represents Inorder of Binary Search tree or not
  178. Find the sum of last n nodes of the given Linked List
  179. Find two numbers from their sum and XOR
  180. Maximize matrix as per given condition
  181. Subarray Inversions
  182. Count quadruples from four sorted arrays whose sum is equal to a given value x
  183. Find k-th bit in a binary string created by repeated invert and append operations
  184. Master Theorem For Subtract and Conquer Recurrences
  185. Find length of loop in linked list
  186. Find a string such that every character is lexicographically greater than its immediate next character
  187. Check if binary representation of a given number and its complement are anagram
  188. Construct a complete binary tree from given array in level order fashion
  189. Longest Prime Subarray after removing one element
  190. Find any one of the multiple repeating elements in read only array
  191. Minimum Index Sum for Common Elements of Two Lists
  192. Merging two unsorted arrays in sorted order
  193. Longest common substring in binary representation of two numbers
  194. Find the fractional (or n/k - th) node in linked list
  195. Largest number with the given set of N digits that is divisible by 2, 3 and 5
  196. Find modular node in a linked list
  197. Minimize cost of operation to equalize tower heights
  198. Shortest distance between two nodes in BST
  199. An interesting solution to get all prime numbers smaller than n
  200. Given two strings check which string makes a palindrome first
  201. Smallest element in an array that is repeated exactly 'k' times.
  202. A modified game of Nim
  203. Longest Common Substring in an Array of Strings
  204. Insert node into the middle of the linked list
  205. Length of the smallest sub-string consisting of maximum distinct characters
  206. Remove three consecutive duplicates from string
  207. Interleave the first half of the queue with second half
  208. Find the n-th number whose binary representation is a palindrome
  209. Diameter of a Binary Tree in O(n) [A new method]
  210. Longest subsequence where every character appears at-least k times
  211. Binary representation of previous number
  212. Operating System | Program for Next Fit algorithm in Memory Management
  213. DFS for a n-ary tree (acyclic graph) represented as adjacency list
  214. Maximize the binary matrix by filpping submatrix once
  215. Smallest number k such that the product of digits of k is equal to n
  216. Make middle node head in a linked list
  217. Sort string of characters
  218. Unique element in an array where all elements occur k times except one
  219. Count of alphabets having ASCII value less than and greater than k
  220. Largest number with one swap allowed
  221. Check if a string is suffix of another
  222. Sudo Placement[1.4] | BST Traversal
  223. Happy Numbers
  224. Sort a Rotated Sorted Array
  225. Unique cells in a binary matrix
  226. Lexicographically largest subsequence such that every character occurs at least k times
  227. Maximize value of (a[i]+i)*(a[j]+j) in an array
  228. Replace node with depth in a binary tree
  229. Generate permutations with only adjacent swaps allowed
  230. Common characters in n strings
  231. Minimum sum by choosing minimum of pairs from array
  232. Reverse a circular linked list
  233. Lexicographically smallest permutation with distinct elements using minimum replacements
  234. Smallest root of the equation x^2 + s(x)*x - n = 0, where s(x) is the sum of digits of root x.
  235. Distinct permutations of the string | Set 2
  236. Average numbers in array
  237. Count all 0s which are blocked by 1s in binary matrix
  238. Remove all characters other than alphabets from string
  239. Sort an array with swapping only with a special element is allowed
  240. Sorting using trivial hash function
  241. Maximum consecutive numbers present in an array
  242. Count sub-arrays which have elements less than or equal to X
  243. Mirror of matrix across diagonal
  244. Find index of closing bracket for a given opening bracket in an expression
  245. Generate original array from an array that store the counts of greater elements on right
  246. Print Longest Palindromic Subsequence
  247. Unset the last m bits
  248. Length of longest strict bitonic subsequence
  249. Minimum cost to construct a string
  250. Queries for maximum difference between prime numbers in given ranges
  251. Binary Tree (Array implementation)
  252. Find largest element from array without using conditional operator
  253. Largest divisible pairs subset
  254. DFS traversal of a tree using recursion
  255. Form the largest palindromic number using atmost two swaps
  256. Program for triangular patterns of alphabets
  257. Check if the given string is the same as its reflection in a mirror
  258. Minimum difference between groups of size two
  259. Minimum Cost to make two Numeric Strings Identical
  260. Insert a whole linked list into other at k-th position
  261. Find next right node of a given key | Set 2
  262. Palindromic Selfie Numbers
  263. Rank of all elements in an array
  264. Make a loop at k-th position in a linked list
  265. Delete a linked list using recursion
  266. Height of binary tree considering even level leaves only
  267. Check if both halves of the string have at least one different character
  268. Covert string X to an anagram of string Y with minimum replacements
  269. Find the largest node in Doubly linked list
  270. Reduce Hamming distance by swapping two characters
  271. Connell Sequence
  272. Tilt of Binary Tree
  273. Maximum distinct lowercase alphabets between two uppercase
  274. Expression contains redundant bracket or not
  275. Maximum spiral sum in Binary Tree
  276. Leaf nodes from Preorder of a Binary Search Tree (Using Recursion)
  277. Consecutive sequenced numbers in a string
  278. Total numbers with no repeated digits in a range
  279. N Queen in O(n) space
  280. Remove all outgoing edges except edge with minimum weight
  281. Substrings starting with vowel and ending with consonants and vice versa
  282. Non-Repeating Element
  283. Insertion sort to sort even and odd positioned elements in different orders
  284. Program to copy the contents of one array into another in the reverse order
  285. Sorted merge in one array
  286. Program to check if matrix is singular or not
  287. Check given array of size n can represent BST of n levels or not
  288. Count ordered pairs of positive numbers such that their sum is S and XOR is K
  289. Reverse each word in a linked list node
  290. Find the only repetitive element between 1 to n-1
  291. Power Set in Lexicographic order
  292. Sort an array containing two types of elements
  293. Check if two strings are permutation of each other
  294. Schedule jobs so that each server gets equal load
  295. Check if item can be measured using a scale and some weights
  296. Count substrings with each character occurring at most k times
  297. Generate a list of n consecutive composite numbers (An interesting method)
  298. Check if it possible to partition in k subarrays with equal sum
  299. Check if linked list is sorted (Iterative and Recursive)
  300. Number of common base strings for two strings
  301. Find the Largest Cube formed by Deleting minimum Digits from a number
  302. Find nth term of the Dragon Curve Sequence
  303. Find maximum element of each row in a matrix
  304. Maximum product subset of an array
  305. Arithmetic Number
  306. Position of n among the numbers made of 2, 3, 5 & 7
  307. Program to display all alphabets from A to Z in uppercase and lowercase both
  308. Longest substring having K distinct vowels
  309. Number of ways to merge two arrays such retaining order
  310. Print reverse string after removing vowels
  311. Program to reverse a string (Iterative and Recursive)
  312. Check for balanced parentheses in an expression | O(1) space
  313. Minimum bit changes in Binary Circular array to reach a index
  314. Maximum adjacent difference in an array in its sorted form
  315. Reverse String according to the number of words
  316. Maximum product quadruple (sub-sequence of size 4) in array
  317. Add n binary strings
  318. Subtract 1 without arithmetic operators
  319. Check whether the number formed by concatenating two numbers is a perfect square or not
  320. Longest subarray such that adjacent elements have at least one common digit | Set 1
  321. Print concentric rectangular pattern in a 2d matrix
  322. Design a stack to retrieve original elements and return the minimum element in O(1) time and O(1) space
  323. Multiset Equivalence Problem
  324. Sort the biotonic doubly linked list | Set-2
  325. Find a Symmetric matrix of order N that contain integers from 0 to N-1 and main diagonal should contain only 0's
  326. Find the number of operations required to make all array elements Equal
  327. Convert a Binary Tree such that every node stores the sum of all nodes in its right subtree
  328. Recursive program to generate power set
  329. Number of permutations such that sum of elements at odd index and even index are equal
  330. Degree of a Cycle Graph
  331. Minimum inverting factor in an array
  332. Minimum steps needed to cover a sequence of points on an infinite grid
  333. Make all numbers of an array equal
  334. Remove leading zeros from an array
  335. Remove edges connected to a node such that the three given nodes are in different trees
  336. Number of Larger Elements on right side in a string
  337. Print cousins of a given node in Binary Tree | Single Traversal
  338. Permutation of a string with maximum number of characters greater than its adjacent characters
  339. Reduce string to shortest length by deleting a pair of same adjacent characters
  340. Replace every element with the greatest element on its left side
  341. Check if concatenation of two strings is balanced or not
  342. Lexicographically smallest string formed by appending a character from the first K characters of a given string
  343. Sudo Placement[1.3] | Stack Design
  344. Number of Counterclockwise shifts to make a string palindrome
  345. Delete all the nodes from the doubly linked list that are greater than a given value
  346. First non-repeating character using one traversal of string | Set 2
  347. Replace every character of string by character whose ASCII value is K times more than it
  348. Sudo Placement[1.5] | Wolfish
  349. Sum of all prime divisors of all the numbers in range L-R
  350. Number of elements smaller than root using preorder traversal of a BST
  351. Find indices of all occurrence of one string in other
  352. Possible number of Rectangle and Squares with the given set of elements
  353. Count pairs with Bitwise XOR as ODD number
  354. Saddleback Search Algorithm in a 2D array
  355. Flatten a binary tree into linked list | Set-2
  356. Delete array element in given index range [L - R]
  357. Number of integral solutions for equation x = b*(sumofdigits(x)^a)+c
  358. Sum of all elements repeating 'k' times in an array
  359. Total sum except adjacent of a given node in a Binary Tree
  360. Bubble Sort On Doubly Linked List
  361. Difference between fundamental data types and derived data types
  362. Minimum multiplications with {2, 3, 7} to make two numbers equal
  363. Minimum number of changes required to make the given array an AP
  364. Printing frequency of each character just after its consecutive occurrences
  365. Balanced expressions such that given positions have opening brackets | Set 2
  366. Minimum element in a max heap
  367. Check if Queue Elements are pairwise consecutive
  368. Modulo power for large numbers represented as strings
  369. Check if the first and last digit of the smallest number forms a prime
  370. Sort first k values in ascending order and remaining n-k values in descending order
  371. Find kth node from Middle towards Head of a Linked List
  372. Convert an Array to a Circular Doubly Linked List
  373. Find Nth term of series 1, 4, 15, 72, 420...
  374. Recursive Approach to find nth node from the end in the linked list
  375. Longest subarray having maximum sum
  376. Reverse a doubly circular linked list
  377. LIFO (Last-In-First-Out) approach in Programming
  378. Remove duplicates from a string in O(1) extra space
  379. Check if a number is divisible by 41 or not
  380. Count elements that are divisible by at-least one element in another array
  381. Rat in a Maze | Backtracking using Stack
  382. Find Nth term (A matrix exponentiation example)
  383. Generating subarrays using recursion
  384. Recursively Reversing a linked list (A simple implementation)
  385. Find a palindromic string B such that given String A is a subsequense of B
  386. Find any pair with given GCD and LCM
  387. Count the number of ways to traverse a Matrix
  388. Count numbers (smaller than or equal to N) with given digit sum
  389. Delete all the nodes from a doubly linked list that are smaller than a given value
  390. Maximum and Minimum element of a linked list which is divisible by a given number k
  391. Find number of magical pairs of string of length L
  392. Check if Queue Elements are pairwise consecutive | Set-2
  393. Remove a given word from a String
  394. Ways to write N as sum of two or more positive integers | Set-2
  395. Replace even nodes of a doubly linked list with the elements of array
  396. Delete all nodes from the doubly linked list which are divisible by K
  397. Number of balanced bracket subsequence of length 2 and 4
  398. Replace minimal number of characters to make all characters pair wise distinct
  399. Program to print the Zigzag pattern
  400. Find the largest good number in the divisors of given number N
  401. How to access elements of a Square Matrix
  402. Meta Binary Search | One-Sided Binary Search
  403. Product of all nodes in a doubly linked list divisible by a given number K
  404. Check if it is possible to return to the starting position after moving in the given directions
  405. Find Sum of pair from two arrays with maximum sum
  406. Pair with given sum in matrix
  407. Check if a pair with given absolute difference exists in a Matrix
  408. Sum of squares of Fibonacci numbers
  409. Remove BST Keys in a given Range
  410. Ulam Number Sequence
  411. Sum of all prime numbers in an Array
  412. Find pairs with given product in a sorted Doubly Linked List
  413. Check if there exists any sub-sequence in a string which is not palindrome
  414. Program to Print Mirrored Hollow Parallelogram
  415. Sum of Fibonacci numbers at even indexes upto N terms
  416. Check if a pair with given product exists in Linked list
  417. Sort prime numbers of an array in descending order
  418. How to convert Vector to array in Java
  419. Search in a sorted 2D matrix (Stored in row major order)
  420. Rearrange all elements of array which are multiples of x in increasing order
  421. Maximum no. of contiguous Prime Numbers in an array
  422. Remove characters from string that appears strictly less than K times
  423. Check if any permutation of N equals any power of K
  424. Check if it is possible to rearrange a binary string with alternate 0s and 1s
  425. Check if there is any pair in a given range with GCD is divisible by k
  426. Get K-th letter of the decoded string formed by repeating substrings
  427. Check if a string contains a palindromic sub-string of even length
  428. Replace every elements in the array by its frequency in the array
  429. Find the foot of perpendicular of a point in a 3 D plane
  430. Remove elements from the array whose frequency lies in the range [l, r]
  431. Find number of cavities in a matrix
  432. Immediate smallest number after re-arranging the digits of a given number
  433. Replace every array element by sum of previous and next
  434. Assign other value to a variable from two possible values
  435. Minimize Cost with Replacement with other allowed
  436. Replace consonants with next immediate consonants alphabetically in a String
  437. Sum and Product of all the nodes which are less than K in the linked list
  438. XOR of all Prime numbers in an Array
  439. Check whether it is possible to make both arrays equal by modifying a single element
  440. Check whether all the rotations of a given number is greater than or equal to the given number or not
  441. Check whether product of digits at even places of a number is divisible by K
  442. Longest subarray with elements having equal modulo K
  443. N digit numbers divisible by 5 formed from the M digits
  444. Replace every element with the smallest element on its left side
  445. Replace each element by the difference of the total size of the array and frequency of that element
  446. Check if the Xor of the frequency of all digits of a number N is zero or not
  447. Magical Pattern
  448. Program to print hollow Triangle pattern
  449. Find the count of palindromic sub-string of a string in its sorted form
  450. Check whether a given binary tree is skewed binary tree or not?
  451. Minimum swaps to group similar characters side by side?
  452. Count the number of words having sum of ASCII values less than and greater than k
  453. XOR of all elements of array with set bits equal to K
  454. Find the value of f(n) / f(r) * f(n-r)
  455. Infix to Postfix using different Precedence Values for In-Stack and Out-Stack
  456. Maximum litres of water that can be bought with N Rupees
  457. Find the player who rearranges the characters to get a palindrome string first
  458. Check whether the frequencies of all the characters in a string are prime or not
  459. Program to remove consonants from a String
  460. Double ended priority queue
  461. Check if two nodes are in same subtree of the root node
  462. Check if the given push and pop sequences of Stack is valid or not
  463. Sort perfect squares in an array at their relative positions
  464. Number of ways to reach the end of matrix with non-zero AND value
  465. Program to convert the diagonal elements of the matrix to 0
  466. Find minimum steps required to reach the end of a matrix | Set - 1
  467. Sum of elements whose square root is present in the array
  468. Reverse middle words of a string
  469. Check if the given decimal number has 0 and 1 digits only
  470. Program to print the given H Pattern
  471. Update adjacent nodes if the current node is zero in a Singly Linked List
  472. Check if moves in a stack or queue are possible or not
  473. Recursive program to print all subsets with given sum
  474. Add index to characters and reverse the string
  475. Count of Numbers in a Range where digit d occurs exactly K times
  476. Difference between Recursion and Iteration
  477. Buy minimum items without change and given coins
  478. Convert a String into a square matrix grid of characters
  479. Check if a number is perfect square without finding square root
  480. Represent n as the sum of exactly k powers of two | Set 2
  481. Find probability that a player wins when probabilities of hitting the target are given
  482. Number of subarrays have bitwise OR >= K
  483. Count of pairs violating BST property
  484. Smallest multiple of 3 which consists of three given non-zero digits
  485. Largest right circular cylinder that can be inscribed within a cone which is in turn inscribed within a cube
  486. Count distinct elements in an array
  487. Check if a string can be repeated to make another string
  488. Check whether the given character is in upper case, lower case or non alphabetic character
  489. Find safe cells in a matrix
  490. Find the Side of the smallest Square that can contain given 4 Big Squares
  491. Check if a number can be represented as a sum of 2 triangular numbers
  492. Minimum replacements to make adjacent characters unequal in a ternary string
  493. Closest sum partition (into two subsets) of numbers from 1 to n
  494. Form lexicographically smallest string with minimum replacements having equal number of 0s, 1s and 2s
  495. Number of sub-strings that contain the given character exactly k times
  496. Lexicographically largest sub-sequence of the given string
  497. Number of ways to choose an integer such that there are exactly K elements greater than it in the given array
  498. Sum of minimum elements of all possible sub-arrays of an array
  499. Find sub-matrix with the given sum
  500. Program to reverse a linked list using Stack
  501. Print Leaf Nodes at a given Level
  502. DFA for accepting the language L = {an bm | n+m=odd}
  503. Find a positive number M such that gcd(N^M, N&M) is maximum
  504. Given two binary strings perform operation until B > 0 and print the result
  505. Smallest Special Prime which is greater than or equal to a given number
  506. Split the array into odd number of segments of odd lengths
  507. Maximum Bitwise AND pair from given range
  508. Sum of all Submatrices of a Given Matrix
  509. Count array elements that divide the sum of all other elements
  510. Find Nth positive number whose digital root is X
  511. Sum of bitwise AND of all submatrices
  512. Number of connected components in a 2-D matrix of strings
  513. Longest subsequence such that adjacent elements have at least one common digit
  514. Minimum changes required to make a Catalan Sequence
  515. Two equal sum segment range queries
  516. Count of all even numbers in the range [L, R] whose sum of digits is divisible by 3
  517. Sum of numbers from 1 to N which are in Lucas Sequence
  518. Bitwise OR of N binary strings
  519. Minimize sum of adjacent difference with removal of one element from array
  520. Group consecutive characters of same type in a string
  521. Probability of A winning the match when individual probabilities of hitting the target given
  522. Minimum number of replacements to make the binary string alternating | Set 2
  523. Longest double string from a Palindrome
  524. Minimum number of bracket reversals needed to make an expression balanced | Set - 2
  525. Sum of the series (1*2) + (2*3) + (3*4) + ...... upto n terms
  526. Numbers that are not divisible by any number in the range [2, 10]
  527. Find the K-th minimum element from an array concatenated M times
  528. Maximum number that can be display on Seven Segment Display using N segments
  529. Program to calculate the value of nPr
  530. Check if the given array is mirror-inverse
  531. Minimum steps to make all the elements of the array divisible by 4
  532. Character whose frequency is equal to the sum of frequencies of other characters of the given string
  533. Addition of two numbers without propagating Carry
  534. Find the sum of all Truncatable primes below N
  535. Minimum cuts required to convert a palindromic string to a different palindromic string
  536. Find maximum N such that the sum of square of first N natural numbers is not more than X
  537. Generate array with minimum sum which can be deleted in P steps
  538. Check if matrix can be converted to another matrix by transposing square sub-matrices
  539. Minimum changes required such that the string satisfies the given condition
  540. Find if the given number is present in the infinite sequence or not
  541. Find the number of good permutations
  542. Check if the given array can be reduced to zeros with the given operation performed given number of times
  543. Minimum length of square to contain at least half of the given Coordinates
  544. Count integers in a range which are divisible by their euler totient value
  545. Number of ways to make binary string of length N such that 0s always occur together in groups of size K
  546. Count sub-arrays whose product is divisible by k
  547. Find foot of perpendicular from a point in 2 D plane to a Line
  548. Find a pair from the given array with maximum nCr value
  549. Minimum steps to delete a string by deleting substring comprising of same characters
  550. Find a distinct pair (x, y) in given range such that x divides y
  551. Find the number of ways to divide number into four parts such that a = c and b = d
  552. Find 2^(2^A) % B
  553. Check if the given binary tree has a sub-tree with equal no of 1's and 0's | Set 2
  554. Maximize the value of the given expression
  555. Programs for printing pyramid patterns using recursion
  556. Sum of Fibonacci Numbers in a range
  557. Minimize the cost to split a number
  558. Count of sub-arrays whose elements can be re-arranged to form palindromes
  559. Partition the array into three equal sum segments
  560. Determine the numer of squares that line will pass through
  561. Find the good permutation of first N natural numbers
  562. Sum of degrees of all nodes of a undirected graph
  563. Sort ugly numbers in an array at their relative positions
  564. Reverse Clockwise spiral traversal of a binary tree
  565. Count of sub-strings that do not contain all the characters from the set {'a', 'b', 'c'} at the same time
  566. XOR of all the elements in the given range [L, R]
  567. Find maximum in stack in O(1) without using additional stack
  568. Find the final radiations of each Radiated Stations
  569. Find number of edges that can be broken in a tree such that Bitwise OR of resulting two trees are equal
  570. Sum of nodes in a linked list which are greater than next node
  571. Count number of binary strings of length N having only 0's and 1's
  572. Length of the smallest number which is divisible by K and formed by using 1's only
  573. Find the number of binary strings of length N with at least 3 consecutive 1s
  574. Reduce the fraction to its lowest form
  575. Iterative selection sort for linked list
  576. Print path from root to all nodes in a Complete Binary Tree
  577. Insert N elements in a Linked List one after other at middle position
  578. Find the minimum number of operations required to make all array elements equal
  579. Sum of all distinct nodes in a linked list
  580. Sum of smaller elements of nodes in a linked list
  581. Count of quadruplets with given Sum
  582. Queries to answer the number of ones and zero to the left of given index
  583. Check if two strings are same ignoring their cases
  584. Find the sum of the number of divisors
  585. Queries to check if substring[L...R] is palindrome or not
  586. Count pairs of non-overlapping palindromic sub-strings of the given string
  587. Given a string and an integer k, find the kth sub-string when all the sub-strings are sorted according to the given condition
  588. Check whether the given string is a valid identifier
  589. Find the nth term of the given series
  590. Find the sum of leafs at maximum level
  591. Queries to update a given index and find gcd in range
  592. Remove all occurrences of any element for maximum array sum
  593. Highest power of a number that divides other number
  594. Maximum elements which can be crossed using given units of a and b
  595. Sum of the series 1, 2, 4, 3, 5, 7, 9, 6, 8, 10, 11, 13.. till N-th term
  596. Check if given two straight lines are identical or not
  597. Find sum of factorials in an array
  598. Count of quadruplets with given Sum | Set 2
  599. Find the Diameter or Longest chord of a Circle
  600. Determine the position of the third person on regular N sided polygon
  601. Length of the chord of the circle whose radius and the angle subtended at the center by the chord is given
  602. Reorder the position of the words in alphabetical order
  603. Given two arrays count all pairs whose sum is an odd number
  604. Print steps to make a number in form of 2^X - 1
  605. Length of the direct common tangent between two externally touching circles
  606. Maximize the given number by replacing a segment of digits with the alternate digits given
  607. Count unique numbers that can be generated from N by adding one and removing trailing zeros
  608. Find element with the maximum set bits in an array
  609. Minimum number of cubes whose sum equals to given number N
  610. Generate an array of K elements such that sum of elements is N and the condition a[i] < a[i+1] <= 2*a[i] is met | Set 2
  611. Calculate score for the given binary string
  612. Count number of 1s in the array after N moves
  613. Area of plot remaining at the end
  614. Count number of subsets whose median is also present in the same subset
  615. Ratio of the distance between the centers of the circles and the point of intersection of two direct common tangents to the circles
  616. Maximum sum path in a matrix from top to bottom and back
  617. Create a sequence whose XOR of elements is y
  618. Count squares with odd side length in Chessboard
  619. Find minimum steps required to reach the end of a matrix | Set 2