# Data Structures in C++: An Interview Refresher (Coderust)

Introduction to Hashing - A Quick Overview of Hash Tables Let’s combine all the different operations discussed previously and test out the functionality of our complete hash table class. Introduction to Stack/Queues - Stack (Implementation) In this lesson, we are going to look at how Stacks are implemented in C++ and how the main Stack functions actually work Introduction to Hashing - Challenge 1: An Array as a Subset of Another Array Can you find whether a given array is a subset of another array by using a hash table? Introduction to Hashing - Solution Review: Find Symmetric Pairs in an Array This review provides a detailed analysis of the different ways to solve the Find Symmetric Pairs in an Array Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5681162219421696). Introduction to Graphs - Solution Review: Find "Mother Vertex" in a Graph This review provides a detailed analysis of the different ways to solve the Find "Mother Vertex" in a Graph challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5703702744662016). Introduction to Trees - 2-3 Insertion This lesson will explain the how insertion is done in 2-3 Trees based on multiple scenarios which are explained in the insertion algorithm. Introduction to Graphs - Solution Review: Implement Depth First Search This review provides a detailed analysis of the different ways to solve the Implement Breadth First Search challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5727060924301312). Introduction to Complexity Measures - Common Complexity Scenarios This lesson summarizes our discussion of complexity measures and includes some commonly used examples and handy formulae to help you with your interview. Introduction to Hashing - Solution Review: Trace the Complete Path of a Journey This review provides a detailed analysis of the different ways to solve the Trace the Complete Path of a Journey Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5746196614217728). Introduction to Linked Lists - Solution Review: Insertion at Tail This review provides a way to solve the Insertion at Tail challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5712679226310656). Introduction to Arrays - Arrays Quiz: Test Your Understanding of Arrays Top ten most commonly asked interview questions about arrays will be covered in this lesson in the form of a quiz. Introduction to Linked Lists - Solution Review: Return the Nth Node from the End This review provides a detailed analysis of how to solve the Return the Nth Node from the End in a Linked List challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/6197310451089408). Introduction to Arrays - Solution Review: Right Rotate an Array This review provides a detailed analysis of the different ways to solve the Right Rotate an array challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5701265350721536). Introduction to Stack/Queues - Solution Review : Evaluate Postfix Expression Using a Stack This review provides a detailed analysis of the different ways to solve the Evaluate Postfix Expression Using Stack challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5719074432614400). Introduction to Linked Lists - Solution Review: Search in a Singly Linked List This review provides a detailed analysis of how we solve the Search in a Singly Linked List challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5679350280093696). Introduction to Linked Lists - Solution Review: Find the Length of a Linked List This review provides a detailed analysis of how to solve the Find the Length of a Linked List challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5685187140648960). Introduction to Linked Lists - Solution Review: Detect a Loop in a Linked List This review provides a detailed analysis of how to solve the Detect a Loop in a Linked List challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/6287032317902848). Introduction to Graphs - Graph Implementation This lesson will cover the implementation of a unidirectional graph via adjacency list in C++. We will also go through the time complexity of basic graph operations. Introduction to Graphs - Solution Review: Implement Breadth First Search This review provides a detailed analysis of the different ways to solve the Implement Breadth First Search challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5660403031867392). Trie - Solution Review: Word Formation From a Vector Using a Trie This review provides a detailed analysis of the different ways to solve the Word Formation From a Vector Using a Trie Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5667240082931712). Trie - Solution Review: List Sort Using Tries This review provides a detailed analysis of the different ways to solve the Array Sort Using Tries Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5707166098915328). Summary of Data Structures - Conclusion And that's a wrap! We hope you had fun taking this course View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5744981138472960). Introduction to Stack/Queues - Solution Review : Implementing Two Stacks using one Array This review provides a detailed analysis of the different ways to solve the Implementing Two Stacks using one Array challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5738522044530688). Introduction to Arrays - Solution Review: Find Second Maximum Value in an Array This review provides a detailed analysis of the different ways to solve the Find Second Maximum Value in an array challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5132285263216640). Introduction to Graphs - Types of Graphs This lesson showcases the two main categories of graphs. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5652096565116928). Introduction to Graphs - Solution Review: Count the Number of Edges in a Graph This review provides a detailed analysis of the different ways to solve the Count the Number of Edges in Graph Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5736232826961920). Introduction to Trees - Solution Review : Find Nodes at "k" distance from the Root This review provides a detailed analysis of the different ways to solve the Find Nodes at "k" distance from the Root challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5675342538735616). Introduction to Trees - Implementing a Binary Search Tree in C++ In this lesson, we'll implement a very basic Binary Search Tree in C++ View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5755997729587200). Introduction to Complexity Measures - Challenge 2: Big (O) of Nested Loop with Subtraction Compute Big(O) of an algorithm which involves nested loops and the loop variables decrement. Introduction to Arrays - Solution Review: Remove Even Integers From an Array This review provides a detailed analysis of how to solve the remove even integers from an array challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5698311486963712). Introduction to Arrays - Solution Review: Find First Unique Integer in an Array This review provides a detailed analysis of the different ways to solve the First Non-Repeating Integer in an array challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5635792869261312). Introduction to Arrays - What is an Array? This lesson briefly defines arrays, their types, and the difference between one dimensional and two dimensional arrays. We will also discuss how arrays are stored in memory. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5745493850193920). Trie - Solution Review: Total Number of Words in a Trie This review provides a detailed analysis of the different ways to solve the Total Number of Words in a Trie Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5678724825481216). Introduction to Trees - Solution Review: Find the Height of a Binary Tree This review provides a detailed analysis of the different ways to solve the Find the Height of a Binary Tree challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5714237762568192). Introduction to Linked Lists - Solution Review: Deletion by Value This review provides a detailed analysis of how to solve the Deletion by Value challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5161132411060224). Introduction to Trees - Challenge 4: Find the Height of a Binary Tree Given the root to a Binary Search Tree, write a function to find the height of the tree. A solution is placed in the “solution” section for your help, but we would suggest you to solve it on your own first. Trie - Challenge 1 : Total Number of Words in a Trie For your first challenge regarding tries, you’ll be writing a very commonly used function which gives us the trie word count. Introduction to Trees - Trees Quiz: Test your understanding of Trees Top ten most commonly asked interview questions about tree will be covered in this lesson in the form of a quiz. Introduction to Heap - Solution Review: Find k largest elements in the Vector In this lesson, we'll look at the solution of challenge, we have covered in the last lesson. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5736829290545152). Introduction to Trees - An Introduction to Trees and Basic Tree Properties! In this chapter, we are going to study the basics of the tree data structure! Introduction to Hashing - Challenge 6 : A Subarray with a Sum of 0 In this exercise, we will find a subarray whose sum turns out to be zero. Let’s try it out! Introduction to Arrays - Solution Review: Rearrange Sorted Array in Max/Min Form This review provides a detailed analysis to solve the Re-arrange Sorted Array in Max/Min Form challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5737480514961408). Introduction to Heap - Min Heap: Introduction This lesson will give a brief introduction to Min-Heaps and how elements are inserted and removed from them Introduction to Arrays - Solution Review : Rearrange Positive & Negative Values This review provides a detailed analysis of the different ways to solve the Rearrange Positive & Negative Values challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5672265731538944). Introduction to Trees - In-Order Traversal In this lesson, we will cover In-Order Traversal and implement it in C++. Introduction to Graphs - Challenge 7 : Check if Given Graph is Tree or not In this lesson, we will learn the difference between a graph and a tree. You will use this knowledge for the challenge below. Introduction to Trees - What is a Binary Search Tree (BST)? This lesson will introduce Binary Search Trees and their properties. Introduction to Complexity Measures - Comparing Algorithms In this lesson, we are going to learn how two or more algorithms may be compared. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5695219446054912). Introduction to Stack/Queues - Solution Review : Sort Values in Stack This review provides a detailed analysis of the different ways to solve the Sort Values in a Stack challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5653241173901312). Introduction to Stack/Queues - Solution Review : Generate Binary Numbers from 1 to n using Queue This review provides a detailed analysis to solve the Generate Binary Numbers from 1 to n using Queue challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5717244776546304). Introduction to Heap - Heap Quiz: Test your understanding of Heaps Here are the top ten most commonly asked interview questions on heaps! Introduction to Hashing - Solution Review: Find Two Pairs Such That a+b = c+d This review provides a detailed analysis of the different ways to solve the Find Two Pairs Such That a+b = c+d Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5633049995771904). Trie - Structure of a Trie This lesson covers the structure of the Trie class in C++. Introduction to Trees - 2-3-4 Trees This lesson is a brief introduction to 2-3-4 Trees. We will discuss its key features and take a look at its examples. Introduction to Trees - Binary Search Tree Insertion In this lesson, we’ll study the binary search tree insertion algorithm! Introduction to Trees - More on Complete Binary Trees In this lesson, we are going to discuss what Complete Binary Trees are and how elements are inserted into them. Introduction to Trees - What is 2-3 Tree? This lesson is an introduction to 2-3 trees, its properties, and an example with the basic operations that this data structure offers. Introduction to Trees - Skewed Binary Trees In this lesson, we will discuss another type of Binary Tree called Skewed Binary Tree. We will look at some of its properties and types. Trie - Deletion in Trie After insertion and search, let’s figure out the logic behind deletion in tries. Introduction to Graphs - What is a Graph? This lesson is a brief introduction to the graph data structure, its types, and the standard terminologies used to describe it. Introduction to Trees - 2-3 Deletion (Case #1) This lesson will cover the deletion operation in 2-3 trees, discussing all the four scenarios based on the position of the element which needs to be deleted. Introduction to Trees - Post-Order Traversal In this lesson, we will cover Post-Order Traversal in a Binary Search Tree and implement it in C++ Introduction to Complexity Measures - Example 1: Measuring Time Complexity of a Single Loop Algorithm In this lesson, we are going to learn how to compute the time complexity of an algorithm that involves a for loop. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5691082318807040). Introduction to Stack/Queues - Challenge 1 : Generate Binary Numbers from 1 to n using Queue Can you generate binary numbers from 1 to any given number “n”? Introduction to Heap - Max Heap: Introduction This lesson will give a brief introduction to Max-Heaps and how their elements are inserted or removed from Max-Heaps. Introduction to Hashing - Hashing Quiz: Test your understanding of Hashing Top ten most commonly asked interview questions about hashing will be covered in this lesson in form of a quiz. Introduction to Trees - Searching in a Binary Search Tree (Implementation) This lesson is about Searching in Binary Search Tree and how to implement searching functionality in C++. Introduction to Arrays - Challenge 1: Remove Even Integers From an Array Given an array, remove all even integers from it. Implement this solution in C++ and see if it runs without an error. Introduction to Linked Lists - Challenge 9 : Union & Intersection of Linked Lists In this lesson, linked lists meet data set operations. Introduction to Graphs - Solution Review: Detect Cycle in Graph This review provides a detailed analysis of the different ways to solve the Detect a Cycle in a Graph challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5641906755207168). Introduction to Heap - Solution Review : Find k smallest elements in a List Have questions about Solution Review : Find k smallest elements in a List? Go for it! View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5670377556541440). Introduction to Graphs - Solution Review: Check if a Graph is a Tree or Not This review provides a detailed analysis of the different ways to solve the Count the Number of Edges in Graph Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5719980670713856). Introduction to Graphs - Challenge 9: Remove Edge In this challenge, we will learn how to delete an edge between two vertices. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5710396451192832). Introduction to Graphs - Challenge 3 : Detect Cycle in Graph Here’s another coding challenge on graphs. You’ll implement a cool function which detects loops! Introduction to Linked Lists - Singly Linked List Insertion Let’s look at the C++ implementation for the insertion of a node in a linked list. Introduction to Linked Lists - Challenge 5 : Reverse a Linked List Can we implement a program which could reverse a linked list? Let’s find out. Trie - Challenge 2 : Find All Words Stored in Trie If you are given a trie, can you return every word it contains? Introduction to Hashing - Solution Review: Check if Arrays are Disjoint This review provides a detailed analysis of the different ways to solve the Check if Arrays are Disjoint Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5710161838604288). Introduction to Linked Lists - Deletion in a Singly Linked List After insertion and search, we’ll be tackling the concept of deletion in a linked list. Introduction to Stack/Queues - What is a Queue? This lesson gives an introduction to the queue data structure, its various uses, and types. We will also go through the inner workings of a Queue by briefly discussing each of its functions. Introduction to Graphs - Challenge 8 : Find the Shortest Path between Two Vertices We’ve dealt with several graph traversals. Now, we’ll find the shortest path traversal between to vertices. Introduction to Hashing - Trie vs Hash Table This lesson highlights the differences between trie and hash tables. Introduction to Graphs - Solution Review: Find the Shortest Path Between Two Vertices This review provides a detailed analysis of the different ways to solve the Find the Shortest Path Between Two Vertices Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5687682516647936). Introduction to Trees - Solution : Find minimum value in Binary Search Tree This review provides a detailed analysis of the different ways to solve the Find minimum value in Binary Search Tree challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5666224323166208). Introduction to Stack/Queues - Solution Review : min() Function Using a Stack This review provides a detailed analysis of the different ways to solve the min() Function Using a Stack challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5643517367943168). Introduction to Complexity Measures - Example 2 : Time Complexity of an Algorithm With Nested Loops In this lesson, we will learn how to compute the time complexity of an algorithm that involves nested for loops. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5731601040277504). Introduction to Stack/Queues - Challenge 9 : min() Function Using a Stack Using your knowledge, create an efficient min() function using a stack. Introduction to Complexity Measures - Challenge 4 : Nested Loop with Multiplication (Advanced) A little-advanced exercise based on the Big(O) of an algorithm which involves nested loops and the loop variables increment with multiplication. Introduction to Heap - Min Heap (Implementation) We’ll implement a min heap in this lesson! Introduction to Stack/Queues - Challenge 3: Reversing First k Elements of Queue Can you reverse first “k” elements in a given queue? A solution is placed in the “solution” section for your help, but we would suggest you to solve it on your own first. Introduction to Trees - Red-Black Tree Deletion This lesson will cover the deletion function in Red-Black trees and will discuss all four deletion cases. Introduction to Trees - Overview of Trees A quick overview of trees, its types, and some important formulas to compute height and number of nodes in a tree. Introduction to Stack/Queues - Solution Review : Implement a Queue Using Stacks This review provides a detailed analysis of the different ways to solve the Implement a Queue Using Stacks challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5673461879930880). Introduction to Stack/Queues - Challenge 5 : Sort Values in a Stack In this lesson, we will learn how to sort elements using a stack. Introduction to Stack/Queues - Challenge 6 : Evaluate Postfix Expression Using a Stack Let’s try to compute postfix mathematical expressions using stacks! Introduction to Stack/Queues - Challenge 7 : Next Greater Element Using in Stack Using a stack, can you implement a function to find the next greater element after any given element in an array? Trie - Insertion in a Trie This lesson defines all the cases needed for inserting a word into a trie, along with the Pythonic implementation. Introduction to Stack/Queues - Solution Review : Reversing First k Elements of Queue This review provides a detailed analysis to solve the Reversing First k Elements of Queue challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5700812231671808). Introduction to Stack/Queues - Solution Review : Next Greater Element Using a Stack This review provides a detailed analysis of the different ways to solve the Next Greater Element Using a Stack challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5689765575786496). Introduction to Graphs - Challenge 6 : Check if a path exists between two vertices Given a graph and two vertices, can you write a code to check if a path exists between the two vertices? Introduction to Graphs - Graph Quiz: Test your understanding of Graphs Here are the ten most commonly asked interview questions about graphs. Introduction to Trees - Binary Search Tree Insertion (Implementation) In this chapter, we’ll study the implementation of Binary Search Tree insertion in C++ through the iterative and recursive approaches. Introduction to Complexity Measures - Introduction to Asymptotic Analysis and Big O In this lesson, we will learn about asymptotic notation, an important tool applied to the analysis of algorithms. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5642165526986752). Introduction to Stack/Queues - Challenge 4 : Implement a Queue Using Stacks We have seen the difference between stacks and queues, but is it possible to make one from the other? Let’s find out. Introduction to Trees - Deletion in Binary Search Tree In this lesson, we are going to learn how nodes are deleted in binary search trees. We will take a look at a few node deletion scenarios and what to do in each one. Introduction to Trees - AVL Insertion This lesson will cover the insertion operation in AVL trees, discussing all the four insertion cases. Introduction to Complexity Measures - Useful Formulae In this lesson, we'll study some mathematical formulae that would make calculating time complexity easier! View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5675494473203712). Introduction to Trees - Solution Review: Find Ancestors of a given node in a Binary Tree This review provides a detailed analysis of the different ways to solve the Find Ancestors of a given node in a Binary Tree challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5742571661819904). Introduction to Arrays - Challenge 7: Find Second Maximum Value in an Array Given an array, can you find the second maximum element in the array? Implement your solution in C++ and see if your output matches the correct output! Introduction to Trees - Challenge 5 : Find Nodes at "k" distance from the Root If you are given the root to a Binary Search Tree and a node value “k”, can you write a code to find the nodes at “k” distance from the root? A solution is placed in the “solution” section for your help, but we would suggest you solve it on your own first. Introduction to Complexity Measures - Solution Review : Nested Loop with Multiplication (Pro) This review provides a detailed analysis of how to solve the Nested Loop with Multiplication challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5650387168133120). Introduction to Graphs - Challenge 1 : Implement Breadth First Search Now, we shall build the BFS algorithm in C++ code. Introduction to Graphs - Challenge 2 : Implement Depth First Search After the BFS algorithm, we will now tackle the implementation for Depth First Search. Introduction to Linked Lists - Challenge 3 : Deletion by Value Based on how we handled the deletion at head strategy, let’s write the function for deletion by value. Trie - What is a Trie? This lesson gives a brief introduction to Trie, its properties, and common applications. Trie - Challenge 3 : List Sort Using Tries This lesson is about sorting string lists using tries. Introduction to Arrays - Challenge 4: Array of Products of all Elements Given an array, return an array where each index stores the product of all numbers in the array except the number at the index itself. Introduction to Linked Lists - Challenge 2 : Search in a Singly Linked List This lesson explains how searching is done in a singly linked list. There is also a coding exercise to test your concepts. Introduction to Trees - AVL Deletion This lesson will cover the deletion operation in AVL trees discussing all the four deletion cases. Introduction to Trees - Challenge 1 : Find minimum value in Binary Search Tree Given the root to a Binary Search Tree, write a function to find the minimum value in that tree. A solution is placed in the “solution” section for your help, but we would suggest you solve it on your own first. Introduction to Graphs - Challenge 4 : Find "Mother Vertex" in a Graph Given a graph, can you find a vertex which shares a common edge with all the other vertices? Introduction to Trees - What is an AVL Tree? This lesson is a brief introduction to AVL trees, why they are used, and what makes them more efficient than regular binary search trees Trie - Search in a Trie This lesson defines the algorithm for a word search in a trie. It also highlights the different scenarios which are taken care of in the algorithm. Introduction to Heap - What is a Heap? A brief introduction to Heaps and their uses. We will also discuss the Heap property and how a heap is implemented. Introduction to Heap - Challenge 3: Find k largest elements in the Vector If you are given a vector and any number “k”, can you write a code to find first “k” largest elements using Max-Heap? Introduction to Hashing - Challenge 3 : Find Symmetric Pairs in an Array Now we will implement a symmetry detection algorithm using hash tables. Introduction to Hashing - Challenge 5 : Find two pairs in an array such that a+b = c+d If you are given an array, can you find two pairs such that their sum is equal? Trie - Trie Quiz: Test Your Understanding of Tries We’re at the end of our discussion on tries. Here are a few follow up questions to reinforce your concepts. Introduction to Complexity Measures - Challenge 6 : Nested Loop with Multiplication (Pro) A pro-level exercise based on Big(O) of an algorithm which involves nested loops and the loop variables increment with multiplication and addition. Introduction to Stack/Queues - What is a Stack? An introduction to the Stack data structure, its uses, and its functionality. Introduction to Stack/Queues - Queue (Implementation) Lets look at the basic functionality and implementation of queues in C++! Introduction to Stack/Queues - Challenge 2 : Implement Two Stacks using one Array Can you implement two stacks using a single array? A solution is placed in the “solution” section for your help, but we would suggest you solve it on your own first. Introduction to Stack/Queues - Challenge 8 : Check Balanced Parentheses Using Stack If you are given an expression, can you check if its parentheses are balanced? A solution is placed in the “solution” section for your help, but we would suggest you to solve it on your own first. Introduction to Graphs - What is a Bipartite Graph? Now, we’ll be introduced to a unique graph called the bipartite graph. We will also take a look at some examples to understand the concept better. Introduction to Heap - Challenge 1 : Convert Max-Heap to Min-Heap Given a Max-Heap, convert it into a Min-Heap. A solution is placed in the “solution” section for your help, but we would suggest you solve it on your own first. Introduction to Heap - Challenge 2 : Find k smallest elements in a List Given a list and a number “k” write a function that returns the first “k” smallest elements using a Heap? Introduction to Heap - Solution Review : Convert Max-Heap to Min-Heap Have questions about Solution Review : Convert Max-Heap to Min-Heap? Go for it! View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/6332798952538112). Introduction to Hashing - What is a Hash Table? This lesson is a brief introduction to the hash table data structure and the basic principle behind implementing it. Introduction to Hashing - Collisions in Hash Tables This lesson is about how collisions occur in hashing and the common strategies used in resolving these collisions. Introduction to Hashing - Building a Hash Table from Scratch This lesson is about how hash tables are implemented in C++. Introduction to Hashing - Challenge 2 : Check if Arrays are Disjoint Building upon the previous challenge, we will learn how to check if two arrays are disjoint. Introduction to Complexity Measures - Complexity Quiz: Test your understanding of Complexity The top ten most commonly asked interview questions about Complexity Measure will be covered in this lesson in the form of a quiz. Introduction to Arrays - Multidimensional Arrays In this lesson, we'll be learning about static multidimensional arrays and dynamic multidimensional arrays. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5747415311187968). Introduction to Linked Lists - Singly Linked Lists (SLL) This lesson is a brief introduction to the functionality and purpose of the popular data structure called linked list. Introduction to Trees - 2-3 Deletion (Case #2) How do we delete an element present at an internal node? It will be explained in this lesson with the help of an example. Introduction to Trees - Pre-Order Traversal In this lesson, we will cover the traversal strategy, ‘Pre-Order Traversal’ in a Binary Search Tree and implement it in C++. Introduction to Arrays - Challenge 2: Merge Two Sorted Arrays Given two sorted arrays, merge them into one array which should also be sorted. Implement the solution in C++ and see if your code runs successfully! Introduction to Stack/Queues - Stack/Queue Quiz: Test your understanding of Stack/Queue Top ten most commonly asked interview questions about stack and queue will be covered in this lesson in form of a quiz. Introduction to Linked Lists - Challenge 4 : Find the Length of a Linked List Let’s write a function which can tell us the length of a linked list. Summary of Data Structures - Overview of Linear & Non-Linear Data Structures In this lesson, we will have review time complexities of all the data structures we have studied. We will also categorize them into linear and non-linear data structures. Introduction to Trees - Challenge 2 : Find kth maximum value in Binary Search Tree Given the root to a Binary Search Tree and a number “k”, write a function to find the kth maximum value in the tree. A solution is placed in the “solution” section for your help, but we would suggest you solve it on your own first. Introduction to Arrays - Solution Review: Merge Two Sorted Arrays This review provides a detailed analysis of the different ways to solve the merge two sorted arrays challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5704393160654848). Introduction to Arrays - Challenge 3: Find Two Numbers that Add up to "value" Given an array and a number <code>value</code>, find two numbers from an array that sum to <code>value</code>. Implement your solution in C++ and see if your output matches with the correct output. Introduction to Trees - What is a Red-Black Tree? This lesson is an introduction to Red-Black trees, their properties, and the total time they take to perform the operations of insertion, deletion, and searching. We will also do a small comparison between AVL and Red-Black Trees. Introduction to Arrays - Solution Review : Find Two Numbers that Add up to "value" This review provides a detailed analysis of the different ways to solve the find two numbers that add up to "value" challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5739975890960384). Introduction to Arrays - Challenge 9: Rearrange Positive & Negative Values Given an array, can you re-arrange its elements in such a way that the negative elements appear at one side and positive elements appear in the other? Solve this problem in C++ and see if your code runs correctly! Introduction to Trees - Challenge 3 : Find Ancestors of a given node in Binary Tree If you are given the root to a Binary Search Tree and a node value “k”, can you write a code to find the ancestor of that node? A solution is placed in the “solution” section for your help, but we would suggest you solve it on your own first. Introduction to Arrays - Solution Review: Array of Products of All Elements This review provides a detailed analysis of how to solve the array of products of all elements challenge! View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5639868793225216). Introduction to Trees - What is a Binary Tree? An introduction to binary trees and different types of binary trees Introduction to Arrays - Challenge 5: Find Minimum Value in an Array Given an array, can you find the minimum value in an array? Implement your solution in C++ and see if your output matches the expected output. Introduction to Arrays - Challenge 10: Rearrange Sorted Array in Max/Min Form Arrange elements in such a way that the maximum element appears at first, then minimum at second, then second maximum at the third position, and second minimum at fourth and so on. Introduction to Linked Lists - Doubly Linked Lists (DLL) After singly linked lists, we’ve come to the more evolved version of the linked list data structure: doubly linked lists. Introduction to Arrays - Solution Review : Find Minimum Value in an Array This review provides a detailed analysis of the different ways to solve the find minimum value in array challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5734439678115840). Introduction to Arrays - Challenge 6: Find First Unique Integer in an Array Given an array, find the first integer which is unique in the array. Unique means the number does not repeat and appears only once in the whole array. Implement your solution in C++ and see if it runs correctly! Introduction to Linked Lists - Challenge 8 : Remove Duplicates from Linked List In this lesson, you must figure out the c++ solution for removing duplicates from a linked list. Introduction to Linked Lists - Linked Lists Quiz: Test your understanding of Linked Lists The top ten most commonly asked interview questions about linked list will be covered in this lesson in the form of a quiz. Introduction to Linked Lists - Challenge 1 : Insertion at Tail Now, we’ll tackle the second insertion strategy in linked lists. However, you will be the one implementing it! Introduction to Linked Lists - Challenge 7 : Find Middle Value of Linked List Here’s another interesting coding challenge to test your knowledge on linked lists. Introduction to Graphs - Representation of Graphs Two approaches to represent a graph will be covered in this lesson. Introduction to Graphs - Solution Review: Check if a Path Exists Between Two Vertices This review provides a detailed analysis of the different ways to solve the Check if a Path Exists Between Two Vertices Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5654456649646080). Introduction to Linked Lists - Challenge 10 : Return the Nth node from End Returning the Nth node from the start of a linked list is easy. Can you return Nth node from the end of a list? Introduction to Graphs - Complexities of Graph Operations Let's discuss the performance of the two graph representation approaches. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5690373313658880). Introduction to Linked Lists - Basic Linked List Operations This lesson lists the various operations that can be performed on linked lists View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5728526581891072). Introduction to Linked Lists - Singly Linked Lists vs. Doubly Linked Lists Let's see how the two renditions of the linked list structure fare against each other. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5743314154291200). Introduction to Linked Lists - Solution Review: Remove Duplicates from a Linked List This review provides a detailed analysis of the different ways to solve the Remove Duplicates from a Linked List challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5071410544246784). Introduction to Graphs - Challenge 5 : Count number of Edges in a Graph In this lesson, we will figure out if it’s possible to count the total number of edges in a graph. Introduction to Linked Lists - Solution Review: Find Middle Value of a Linked List This review provides a detailed analysis of how to solve the Find the Middle Value in a Linked List challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5634360497668096). Introduction to Linked Lists - Linked Lists vs. Arrays Let's pit the two data structures against each other to find out which is more efficient. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5696228427825152). Introduction to Trees - What Makes a Tree 'balanced'? In this chapter, we are going to study what makes a tree balanced. We are also going to look at a high-level description of the algorithm used to determine if a given tree is balanced. Introduction to Linked Lists - Solution Review: Union and Intersection of Linked Lists This review provides a detailed analysis of how to solve the Union and Intersection of Linked Lists challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5187211452481536). Introduction to Graphs - Solution Review: Remove Edge This review provides a detailed analysis of the different ways to solve the Remove Edge Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5124732563226624). Introduction to Linked Lists - Solution Review: Reverse a Linked List This review provides a detailed analysis of how to solve the Reverse a Linked List challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5122237187227648). Introduction to Trees - Solution Review : Find kth maximum value in Binary Search Tree This review provides a detailed analysis of the different ways to solve the Find kth maximum value in Binary Search Tree challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5722608653828096). Introduction to Linked Lists - Challenge 6 : Detect Loop in a Linked List Loops in linked lists can be dangerous. Now, you’ll create an algorithm to detect them. Introduction to Hashing - Solution Review: A Subarray with a Sum of 0 This review provides a detailed analysis of the different ways to solve the A Subarray with a Sum of 0 Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5705944180719616). Trie - Challenge 4 : Word Formation From a Vector Using Trie This is a more advanced problem regarding tries and shows us the efficiency of this data structure in word matching. Introduction to Trees - Deletion in Binary Search Tree (Implementation) We will now write the implementation of the deletion function which covers all the cases that we discussed previously. Introduction to Trees - Red-Black Tree Insertion This lesson will cover the insertion operation in Red-Black trees, discussing all the four insertion cases. Introduction to Hashing - Challenge 4 : Trace the Complete Path of a Journey Test your knowledge on hash table traversal with this coding exercise! Trie - Solution Review: Find All Words Stored in Trie This review provides a detailed analysis of the different ways to solve the Find All Words Stored in Trie Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5743939608903680). Introduction to Complexity Measures - Challenge 1: Big (O) of Nested Loop with Addition Compute the Big O complexity of an algorithm which involves nested loops where the loop variables increase with addition. Introduction to Complexity Measures - Challenge 3: Big (O) of Nested Loop with Multiplication Compute Big(O) of an algorithm which involves nested loops and the loop variables increment with multiplication. Introduction to Arrays - Challenge 8: Right Rotate an Array Given an array, can you rotate its elements by one index from right to left? Implement your solution in C++ and see if your code runs successfully! Introduction to Graphs - Graph Traversal Algorithms In this lesson, we will learn the basic logic behind graph traversal and we will see how it applies to the two most famous graph traversal algorithms. Introduction to Hashing - Add/Remove & Search in Hash Table (Implementation) This lesson will cover the C++ Implementation for search, insertion, and deletion in hash tables. Introduction to Heap - Max Heap (Implementation) Let’s implement a max Heap. Introduction to Complexity Measures - Challenge 5 : Nested Loop with Multiplication (Complex) Here’s a more complex exercise to determine the Big(O) time complexity of an algorithm which involves nested loops and the loop variables increment with multiplication. Introduction to Hashing - The Hash Function This is the first building block of a hash table. Let's see how it works. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5758448008429568). Introduction to Hashing - Solution Review: An Array as a Subset of Another Array This review provides a detailed analysis of the different ways to solve the An Array as a Subset of Another Array Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5644534738321408). Introduction to Complexity Measures - Other Common Asymptotic Notations and Why Big O Trumps Them This lesson covers the various asymptotic notations for algorithms and why computer scientists prefer Big O instead of other notations. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5699349795307520). Introduction to Complexity Measures - Solution Review: Big (O) of Nested Loop with Addition This review provides a detailed analysis of the time complexity of the Nested Loop with Addition problem! View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5765183054020608). Introduction to Complexity Measures - Solution Review: Big (O) of Nested Loop with Subtraction This review provides a detailed analysis of how to solve the Big (O) of Nested Loop with Subtraction challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5633722695024640). Introduction to Complexity Measures - Solution Review: Big (O) of Nested Loop with Multiplication This review provides a detailed analysis of how to solve the Big (O) of Nested Loop with Multiplication Challenge. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5705431468998656). Introduction to Complexity Measures - Solution Review : Nested Loop with Multiplication (Advanced) This review provides a detailed analysis of how to solve the nested loop with a multiplication problem. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5666536245166080). Introduction to Complexity Measures - Solution Review : Nested Loop with Multiplication (Complex) Here's a solution review for the exercise in the last lesson. View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5742058950098944). Introduction to Stack/Queues - Solution Review : Check Balanced Parentheses using Stack This review provides a detailed analysis to solve the Check Balanced Parentheses using Stack challenge View the lesson [here](https://www.educative.io/collection/page/5642554087309312/5646276079124480/5754980359208960).

About the Data Structures in C++: An Interview Refresher (Coderust) category
[Data Structures in C++: An Interview Refresher (Coderust)]
(1)

The Solution is wrong
[Introduction to Arrays - Solution Review: Array of Products of All Elements]
(1)

Where is this "i = n;" coming from?
[Introduction to Complexity Measures - Example 1: Measuring Time Complexity of a Single Loop Algorithm]
(1)

Who wrote solutions !? So many basic mistakes!
[Introduction to Linked Lists - Solution Review: Search in a Singly Linked List]
(1)

Graph class missing some methods?
[Introduction to Graphs - Solution Review: Implement Breadth First Search]
(1)

Test Comparing Value Incorrectly
[Introduction to Trees - Challenge 3 : Find Ancestors of a given node in Binary Tree]
(3)