1. Print level order traversal line by line
  2. Print all nodes in a binary tree having K leaves
  3. Print K’th element in spiral form of matrix
  4. Print Common Nodes in Two Binary Search Trees
  5. Vertical Sum in a given Binary Tree
  6. Number of buildings facing the sun
  7. Number of Groups of Sizes Two Or Three Divisible By 3
  8. Pairwise swap elements of a given linked list by changing links
  9. Lowest Common Ancestor in a Binary Search Tree
  10. Find position of an element in a sorted array of infinite numbers
  11. Find the index of first 1 in a sorted array of 0’s and 1’s
  12. Find the index of first 1 in an infinite sorted array of 0s and 1s
  13. Find Index of 0 to be replaced with 1 to get longest continuous sequence of 1s in a binary array
  14. Find zeroes to be flipped so that number of consecutive 1’s is maximized
  15. Maximize number of 0s by flipping a subarray
  16. Check if a binary tree is subtree of another binary tree
  17. Longest Common Substring
    Explanation :- Longest Common Substring
  18. Longest Even Length Substring such that Sum of First and Second Half is same
  19. Maximum size square sub-matrix with all 1s
  20. Maximum size rectangle binary sub-matrix with all 1s
  21. K’th Smallest/Largest Element in Unsorted Array
  22. Matrix Chain Multiplication
  23. Multiply Large Numbers represented as Strings
  24. Length of longest palindrome list in a linked list using O(1) extra space
  25. Find if a string is interleaved of two other strings
    Reference :- Interleaving Strings