## REORDER LIST

Concepts Used Linked List. Difficulty Level Hard. Problem Statement : Given a singly linked list L:L0→L1→…→Ln−1→Ln, reorder it to :L0→Ln→L1→Ln−1→L2→Ln−2→… You must do this in-place without altering the nodes’ values....

## FIND PAIR SUM

Concepts Used Linked lists,hash table Difficulty Level Hard. Problem Statement : Given a sorted singly linked list and a value K, the task is to find pair whose sum is...

## QUICK SORT

Concepts Used Qucik sort. Difficulty Level Hard. Problem Statement : You are given a pointer to the head of a linked list. Now the length of the linked list is...

## MERGE K SORTED LINKED LISTS

Concepts Used Linked lists, Heaps/priority queue(efficient soltution) Difficulty Level Hard Problem Statement : Yor are given K sorted linked lists. You have to merge K sorted linked lists into one...

## DELETE NODES FROM LINKED LIST

Concepts Used Linked lists,reverse a linked list Difficulty Level Medium. Problem Statement : Given a linked list containing N nodes, if the (i+1)th node is greater than the ith node...

## PALINDROME LIST

Concepts Used Linked list,recursion ,stack. Difficulty Level Easy Problem Statement : Check whether the given linked list is a palindrome or not. Example: 2 3 2 5 2 true 5...

## INSERT A NODE

Concepts Used Linked list Difficulty Level Easy Problem Statement : You are given a sorted linked list and you have to insert a node in the list in a sorted...

## Valid Binary Search Tree

Concepts Used DFS , Recursion Difficulty Level Medium Problem Statement : Given a binary tree, determine if it is a valid binary search tree (BST). See original problem statement here...

## Convert SumTree

Concepts Used DFS , Recursion Difficulty Level Medium Problem Statement : Given a binary tree and the task is to convert that tree into SumTree. See original problem statement here...

## Size of Tree

Concepts Used BFS , Recursion Difficulty Level Easy Problem Statement : Given a binary tree, our task is to print the size of the tree. Size of tree represented as...

## Mirror Reflection

Concepts Used DFS , Recursion Difficulty Level Medium Problem Statement : Given two binary trees, we need to find whether one tree in the pair is the mirror image of...

## Maximum Turns

Concepts Used DFS , Recursion Difficulty Level Hard Problem Statement : Given a binary tree, find the path length having maximum number of bends. See original problem statement here Solution...

## LevelOrder Traversal

Concepts Used BFS , Queue Difficulty Level Easy Problem Statement : Given a binary tree, our task is to print the level order traversal of the tree. See original problem...

## Ancestors

Concepts Used DFS , Recursion Difficulty Level Medium Problem Statement : "Lowest common ancestor of two node n1 and n2 is the lowest node in the tree that has both...

## Inorder Traversal

Concepts Used DFS , Recursion, Stack Difficulty Level Easy Problem Statement : Given a binary tree, our task is to print the inorder traversal of the tree. See original problem...

## Height of Tree

Concepts Used BFS , Recursion Difficulty Level Easy Problem Statement : Given a binary tree, our task is to print the height of the tree. Consider root node height as...

## Maximum Distinct

Concepts Used DFS , Recursion, Hashing Difficulty Level Hard Problem Statement : Given a binary tree, our task is to return the maximum count of distinct integers present in a...

## Mirror Tree

Concepts Used DFS , Recursion, Stack Difficulty Level Medium Problem Statement : Given a Binary Tree, convert it into its mirror. See original problem statement here Solution Approach : Introduction:...

## Light in night

CONCEPTS USED: Sorting DIFFICULTY LEVEL: Medium PROBLEM STATEMENT(SIMPLIFIED): Given an array A containing N bulbs placed on the road of length L, these bulbs can be placed at any point...

## Student Marks

Concepts Used Queue, Basic Implementation Difficulty Level Easy Problem Statement : You are given a binary tree, you need to print the average of each level of the tree. See...

## Largest number smaller than or equal to N and digits in non-decreasing order

Concepts Used Strings Difficulty Level Medium Problem Statement (Simplified): For a number given to us, we have to print a number less than or equal to the given number, and...

## Sort in a unique way

Concepts Used: Sorting Difficulty Level: Easy Problem Statement (Simplified): For a given array find the length of largest sorted sub-array in it, but if the current array is not sorted,...

## GCD of two numbers

Concepts Used: Mathematics Difficulty Level: Easy Problem Statement (Simplified): Print gcd of two given numbers. gcd(m,n) is the largest number possible which divides both. See original problem statement here Test...

## GCD of two very large numbers

Concepts Used: Mathematics Difficulty Level: Hard Problem Statement (Simplified): For given two large numbers M and N, find their gcd(M,N). GCD(M,N) is the larget number possible which divides both. See...

## Sort array containing only 0, 1 and 2 as elements

Concepts Used: Sorting Difficulty Level: Easy Problem Statement (Simplified): We have to print the array containing 0s, 1s and 2s in non-decreasing order. See original problem statement here Test Case:...

## Find sum of elements less than A and greater than B in an array

Concepts Used: Sorting Difficulty Level: Medium Problem Statement (Simplified): You're provided an array containing N elements, you have to answer q queries. In each query, you're provided with x and...

## Find the misplaced elements

Concepts Used: Sorting Difficulty Level: Easy Problem Statement (Simplified): Find how many elements change their place after sorting array. See original problem statement here Test case: Input: 1 5 8...

## Convert Integer number to Roman Number

Concepts Used: Strings Difficulty Level: Medium Problem Statement (Simplified): For a given number between 0 and 4000, print out it's Roman Form. See original problem statement here Test Case: Input:...

## Tina loves A

Concepts Used: Strings, Basic Mathematics Difficulty Level: Easy Problem Statement (Simplified): Print the maximum length of string which can be formed such that the number of a is more than...

## Minimum number of operations to make string palindrome

Concepts Used Strings Difficulty Level Easy Problem Statement (Simplified): Convert given string into a palindrome by decreasing or increasing characters by their ASCII value, in minimum number of operations. Each...