Featured Lists Top 20 Problems on Dynamic programming Top 10 Problems on Backtracking Top 20 Problems on Graph Top 25 Problems on Trees Top 10 Problems on Bits Manipulation Top 15 Problems in LinkedList All Problems # Status Problem video Level Completes Likes 56 Sort an Array - odd numbers appear first in ascending order followed by the even numbers in descending order. Medium % 0 55 Print All Nodes Between Two Given Levels Medium % 0 54 Find the maximum width of a binary tree Medium % 0 53 Find the number of occurrences of a number in a given sorted array. Medium % 0 52 Find all common numbers in given three sorted arrays. Beginner % 0 50 Find the first repeated element in an array by its index Medium % 0 49 Minimum number that cannot be formed by any subset of an array Beginner % 0 47 Find the Size of the Binary Tree Beginner % 0 46 Given two binary trees, check if one binary tree is a subtree of another Medium % 0 45 Print a path from Root to Node in Binary Tree Medium % 0 44 Inorder Successor in Binary Tree Medium % 0 35 Adding Two Numbers with Linked Lists Medium % 0 34 Add two numbers represented by a linked list, Numbers are Stored in REVERSE order Medium % 0 31 Reverse a Linked List Using Recursion Medium % 0 25 String Compression using count of repeated characters - Run Length Encoding Beginner % 0 24 Replace Spaces with '%20' Without Using Default Functions Medium % 0 16 Singly Linked List Implementation Beginner % 0 14 Longest Shared Prefix Sequence in a String Medium % 0 13 Print All Elements of Two Dimensional Array in Spiral Order Medium % 0 12 Efficient Methods to Find Pairs with Sum K in an Array Beginner % 0 11 Check If String has All Unique Characters Beginner % 0 10 Quick Sort Implementation Medium % 0 8 Efficient Search in 2D Sorted Array: Find an Element Medium % 0 7 Determine If a String is Palindrome Beginner % 0 6 Find a peak element in a Given Array Beginner % 0 3 Hash Table - Java Beginner % 0 Sort an Array - odd numbers appear first in ascending order followed by the even numbers in descending order. Print All Nodes Between Two Given Levels Find the maximum width of a binary tree Find the number of occurrences of a number in a given sorted array. Find all common numbers in given three sorted arrays. Find the first repeated element in an array by its index Minimum number that cannot be formed by any subset of an array Find the Size of the Binary Tree Given two binary trees, check if one binary tree is a subtree of another Print a path from Root to Node in Binary Tree Inorder Successor in Binary Tree Adding Two Numbers with Linked Lists Add two numbers represented by a linked list, Numbers are Stored in REVERSE order Reverse a Linked List Using Recursion String Compression using count of repeated characters - Run Length Encoding Replace Spaces with '%20' Without Using Default Functions Singly Linked List Implementation Longest Shared Prefix Sequence in a String Print All Elements of Two Dimensional Array in Spiral Order Efficient Methods to Find Pairs with Sum K in an Array Check If String has All Unique Characters Quick Sort Implementation Efficient Search in 2D Sorted Array: Find an Element Determine If a String is Palindrome Find a peak element in a Given Array Hash Table - Java 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16