1. K largest elements from a big file or array
  2. Find a triplet a, b, c such that a2 = b2 + c2
  3. Convert a Binary tree to DLL
  4. Lowest Common ancestor in a Bianry Search Tree and Binary Tree
  5. Implement a stack with push(), pop() and min() in O(1) time
  6. Reverse a linked list in groups of size k
  7. Given two numbers represented by two linked lists, write a function that returns sum list
  8. Rotate a matrix by 90 degree
  9. Stock span problem
    Related blog :- Stock span problem
  10. Next greater element
    Related blog : – Next greater element in an array
  11. Maximum sum subarray such that no elements are consecutive
    Related blog : – Maximum sum such that no two elements are adjacent
  12. Edit distance
    Related blog :- Find minimum edit distance between given two strings
  13. Assembly line scheduling
  14. Ways to write n as sum of two or more positive integers
  15. Binary Search Tree Iterator
  16. K’th smallest element in BST using O(1) Extra Space
  17. Print equal sum sets of array
  18. Ways to arrange Balls such that adjacent balls are of different types
  19. Non-overlapping Intervals
  20. Program to find GCD or HCF of two numbers
  21. Wiggle Sort II
  22. Given an array of of size n and a number k, find all elements that appear more than n/k times
  23. Sum of bit differences among all pairs
  24. Implement Power Function
  25. Allocate minimum number of pages