- Save all leaf nodes of a Binary tree in a Doubly Linked List by using Right node as Next node and Left Node as Previous Node.
- Given an array,find the maximum j – i such that arr[j] > arr[i]
- Remove Alternate Duplicate characters from a char array you have to do it in Place.Like keeping only the odd occurences of each character.
- Example: Input: “you got beautiful eyes”
- Output: ”you gtbeaiful es”
- Allowed Time Complexity was O(n) and Space Complexity was O(1)
- In a file there are 1 million words . Find 10 most frequent words in that file.
- Find all nodes at k-distance from a given node in a binary tree
- Clone a linked list with next and random pointer
- Serialise and Deserialise a linked list with next and random pointer.
- Construct a binary tree from given inorder and preorder traversals.
- Return a tree such that each internal node stores sum of all its child nodes. Each leaf node stores zero.
- How will you implement linked list with 1 million nodes? How will you access 999999 th node? Give some optimal design strategy and implementation.
- Reversal of Linked List in groups of K.
- Given a positive integer N, count all possible distinct binary strings of length N such that there are no consecutive 1’s.
- Check whether given binary tree is balanced or not. Definition was no two leaves should have height difference of greater than one.
- Remove duplicates from string in place in O(n).
- Connect nodes on same level in a binary tree.
- Find sum of data of all leaves of a binary tree on same level and then multiply sums obtained of all levels.
- Given a matrix of characters and a word.
you have to count the number of occurrences of that word in that matrix. you can move to any of the eight valid directions from current position.
- You are given an string as input which represents a path. You have to normalize that path inplace(NO EXTRA SPACE).
- e.g.
- input : "\a\b\c\..\..\file.txt"
- output: "\a\file.txt"
- Least common ancestor of two nodes in a binary tree
- Given two sorted arrays (with repetitive elements) find the kth minimum number from both arrays.
- Given the root to a binary tree, a value n and k.Find the sum of nodes at distance k from node with value n
- Find an element in a rotated array
- Given two linked lists both represent a number. Create a linked list that contains its sum.
- Given a binary search tree , print the path which has the sum equal to k and has minimum hops. i.e if there are multiple paths with the sum equal to k then print the path with minimum number of nodes.
- A MxN matrix containing integers (positive, negative and zero’s). For every position containing 0, mark the corresponding row and column as 0.
- Rotate MxN matrix by 90 degress.
- Find the nth number that contains the digit k or is divisible by k. (2 <= k <= 9)
- Write a program to connect next left node in a binary tree. Also first node of each level should be pointing to last node of next level? (Without using Queue)
- Convert a binary tree to its sum tree(each node is the sum of its children)
- Given a directed graph. Construct another graph from given graph such that if path exists from vertices A to vertices B and from B to C, then path from A to C and from C to A also should exists.
- Implement hashmap on your own. Write good hashing function for string.
- Given an array, arrange the elements such that the number formed by concatenating the elements is highest.
E.g.: input = [9, 93, 24, 6], the output should be: [9,93,6,24]. This is because if you concatenate all the numbers, 993624 is the highest number that can be formed.
- Given a string, find the longest substring which is palindrome.
- Given that integers are read from a data stream. Find median of elements read so for in efficient way. For simplicity assume there are no duplicates.
- Write an efficient program for printing k largest elements in an array. Elements in array can be in any order.
- Given unsorted array and a number K. Find 2 numbers such that sum is K.
- Given n-ary tree. zigzag level order traversal.
- Given string s and string t find whether all permutation of t is present as substring in s.
- Design a stack which holds an integer value such that getMinimum() function should return the minimum element in the stack. Implement popMin() function which would pop minimum element from the original stack.
- Given a set of intervals like 5-10, 15-20, 25-40, 30-45, 50-100. Find the ith smallest number in these intervals. Assume there are no duplicate numbers.
- e.g: 1st smallest number = 5
- 6th smallest number = 10
- 7th smallest number = 15 and so on.
- Given an array which is first strictly increasing and then strictly decreasing. Find an element in this array.
- Given a string example : shoppingwithflipkartiseasy, Now we are given this string and a dictionary containing valid words , now we need to break the sentence into words separated by space. Output : shopping with flipkart is easy
- Given a series 2,3,4,5,6,8,9,10,……, here in this series all the numbers are present which have factors only and only either 2,3 or 5. Need to write a node to generate nth number for the series . With best approach and complexity
- Given a tree with edge weights, find any path in the tree with maximum sum of edges.
- Merge k sorted arrays.
- Given a maze, a start point and end point find the shortest path to reach the end point from the starting point.
- Given a sentence and a set of characters. Find the minimum window within which the set of characters can be found in the sentence in any order.
- You are given a string of 0’s and 1’s you have to find the number of substrings in the string which starts and end with a 1.
- eg : input : 0010110010
- output : 6
- You are given a mapping like a -> 1, b-> 2… z-> 26. You have to print all possible combinations of a given number using the above information.
- eg : input : 121
- output : aba,la,au
- Given a dictionary of 50,000 words. Given a phrase without spaces, add spaces to make it a proper sentence.
- e.g:input: thequickbrownfoxjumpoverlazydog
- output: the quick brown fox jump over lazy dog
- Given an unsorted array of n integers which can contain integers from 1 to n. Some elements can be repeated multiple times and some other elements can be absent from the array. Count frequency of all elements that are present and print the missing elements.
- Examples:Input: arr[] = {2, 3, 3, 2, 5}
- Output: Below are frequencies of all elements
- 1 -> 0 2 -> 2 3 -> 2 4 -> 0 5 -> 1
- Get the next bigger number using the same digits of a number.
Eg, For 123456, next number would be 123465
- Given a boolean 2D matrix, find the number of islands. A group of connected 1s forms an island. For example, the below matrix contains 5 islands
- Input : mat[][] =
- {1, 1, 0, 0, 0},
- {0, 1, 0, 0, 1},
- {1, 0, 0, 1, 1},
- {0, 0, 0, 0, 0},
- {1, 0, 1, 0, 1}
- Output : 5
- This problem is know as Clock angle problem where we need to find angle between hands of an analog clock at a given time.
- Examples:Input: h = 12:00, m = 30.00
- Output: 165 degree
- Input: h = 3.00, m = 30.00
- Output: 75 degree
