1. Longest Palindromic Subsequence
  2. Design a stack that supports getMin() in O(1) time and O(1) extra space
  3. Depth First Traversal or DFS for a Graph
  4. Count Inversions in an array
  5. Extract Leaves of a Binary Tree in a Doubly Linked List
  6. Check if a given sequence of moves for a robot is circular or not
  7. Breadth First Traversal or BFS for a Graph
  8. Boundary Traversal of binary tree
  9. Add all greater values to every node in a given BST
  10. Hamiltonian Cycle
    Explanation :- Hamiltonian path
  11. Sudoku
  12. Count of n digit numbers whose sum of digits equals to given sum
  13. Rat in a Maze
  14. The Knight’s tour problem
  15. Construct a special tree from given preorder traversal
  16. Construct a Binary Tree from Postorder and Inorder
  17. N Queen Problem
    Refernce : N Queen Problem Using Backtracking Algorithm
  18. Binary representation of a given number
  19. Find if two rectangles overlap
  20. Check if a linked list is Circular Linked List
  21. Sort all even numbers in ascending order and then sort all odd numbers in descending order
  22. Convert a Binary Tree into its Mirror Tree
  23. Write your own atoi()
  24. Add two numbers represented by linked lists
  25. K’th Largest Element in BST when modification to BST is not allowed