Break Away Coding Interviews 1

Materials Preview 00:04

Introduction to pointers Preview 19:59

Pointers are the foundation of all hard interview problems, visualizing memory layout using pointers helps us understand what's really happening under the covers.

Pointer problems and arrays Preview 13:34

Practice is the key to understanding key pointer concepts, solve pointer problems by visualizing the memory layout.

Arrays are pointers at heart, work with them exactly like you would with pointers.

Pointer arithmetic Preview 11:43

Pointers know how much space the data they point to occupies. Which means you can access all elements of an array with a single pointer, pointer arithmetic is pretty cool!

Practice makes perfect - pointer problems Preview 07:37

A whole bunch of practice with pointer problems. These should be easy because you will have the memory layout right there to help you visualize things.

Working with strings Preview 14:07

Strings are character pointers which are equivalent to character arrays. Solve functions from the string.h library for practice dealing with pointers.

Pointer as arguments to functions Preview 09:39

Pointers as arguments to functions have subtleties which need to be understood to use them correctly. Understand reassignment and modifications of pointers in a function and see how the original pointers are affected in the calling code.

Practice makes perfect - string problems Preview 19:23

Let's solve some harder problems from the string.h library, remember the little details like string termination, null inputs all matter in an interview!

Pointers to pointers - bend your mind Preview 10:28

Pointers just hold addresses of a memory location, which means we can have pointers to pointers to pointers. Sounds complicated? No worries, there are examples to help you understand these every step of the way.

Pointers to pointers - reassignment and modification Preview 11:13

Pointers to pointers requires a heightened conceptualization of memory layout. See detailed visuals on how pointer modification and reassignment work. User defined types or structs can also have pointers to them, memory layout and visualization of struct pointers.

Get started with linked lists Preview 17:16

Linked lists are favorite interview questions for software engineering roles. If you can work linked lists you're on your way to tackling more complicated problems. Understand the memory set up of linked lists and start with a few problems to gain confidence.

Get the length of a linked list, access the nth element in a list, and append an element to the end of the list - all this while handling null lists and other details.

Warming up to - they get tricky quickly Preview 16:19

For a simple concept, linked lists can get surprisingly tricky very quickly. Practice and practice again to gain mastery over linked list problems.

Use the linked list as a stack and implement pop, delete all the elements in a list - tricky memory freeing here, insert an element at a specified position and in a sorted list - these are similar but the edge cases differ.

Cruising along - linked lists are fun aren't they? Preview 18:59

Once you've actually solved all the examples we've got so far, you'll find that linked lists are fun! This class has a particularly difficult sample problem which will introduce you to the fast and slow pointers which traverse a linked list at different speeds. Useful for a lot of tricky maneuvering.

Append one list to another and split a list into two by using fast and slow pointers. This second problem is much, much harder than it seems.

Autopilot - linked lists are easy after all Preview 16:31

By now you should be able to solve linked list problems in your sleep. Let's practice a few last ones to gain complete master over them.

Remove duplicates from a sorted list, move the first node from one list to another, merge two sorted lists and finally reverse a linked list.

Do not overlook the doubly linked list Preview 10:02

Doubly linked lists lend themselves to fewer interesting problems. However its important to not overlook them, let's try deleting a node in a doubly linked list and see how to work with forward and reverse pointers.

Bit Manipulation - I Preview 10:07

We dig into the bitwise AND, OR and NOT operations - visually inspecting how they work.

Bit Manipulation - II Preview 08:39

We continue with bit manipulation - the right shift and left shift operators are very powerful, but they have 2 issues that you should be sure to understand: overflow, and fill.

Useful Bit Manipulation Techniques Preview 13:13

Before diving headlong into bit manipulation problems it's helpful to learn a few useful tricks which help you build a strong foundation to visualize working with bits.

Get And Set The Nth Bit Preview 13:30

Functions to get the nth bit of an integer and to set the nth bit of an integer. These are the building block functions and the concepts underlying these will be used for harder bit manipulation problems.

Print And Count Bits Preview 18:54

Print all the bits used to represent an integer from the most significant bit to the least significant. Learn some subtle details about the shift right (>>) with negative numbers!

Count the number of 1s in an integer, and learn a neat trick which allows you to do it in complexity O(number of 1s).

Reverse The Bits In An Integer Preview 10:10

Reverse the bits in an integer. This pulls together a whole bunch of stuff from the last few problems. As in the case of hard problems, visualizing the process is key to solving this!

Starting up - palindromes and points within a distance Preview 18:16

During coding interviews you might encounter questions which you can work out from first principles. You should be nailing these! Let's start with figuring out whether a string is a palindrome and finding all the points within a certain distance from another point.

Play the Game Of Life and Break A Document Into Chunks Preview 18:33

Two more problems and detailed solutions. Play the game of life where every cell can change states from live to dead based on its neighbours.

Then move on to breaking a document into chunks to send down to a client subject to very specific constraints.

Run Length Encoding And Adding Numbers Digit By Digit Preview 19:46

Run length encoding involves specifying the number of times a character is repeated in a string. Decoding run-length-encoded strings can be pretty tricky, let's find a solution for both.

If a number were represented by its digits, can you write code to add 2 numbers represented in this way? Let's walk through a solution and see if you can get this right.

Sudoku Board Validation and Incrementing A Number In Another Number System Preview 19:55

Write code to check whether a Sudoku board is valid. This should work for both complete and incomplete boards. Sudoku is tricky and this has many conditions to check.

Lastly set up your own numeric system and then increment a number represented in that system by 1.

Performance and Complexity Preview 16:02

What is the performance of your code? How do you measure this? What is complexity and what is its relationship with performance?

Big O Notation Preview 15:58

The Big O notation is used to express complexity based on the size of the input specified for any algorithm. How is Big O expressed, how is it calculated and many examples to drive the concepts home!

Big O Notation More Examples Preview 19:12

The Big O notation becomes much clearer when you practice find the complexity of some sample pieces of code. Let's see how many of these you get right!

Sorting Trade-Offs Preview 10:52

A sorting algorithm is not just defined by its complexity, there are a whole bunch of other characteristics which can be used to determine which sorting algorithm is the right one for a system. Let's understand what these characteristics are and what are the trade offs we might make.

Selection Sort Preview 15:24

The simplest and most naive sorting algorithm.

Bubble Sort Preview 14:41

Closely allied with selection sort is bubble sort. Its an adaptive sort with the same time complexity as selection sort.

Insertion Sort Preview 14:32

Insertion sort is an improvement over both bubble sort and selection sort. Let's see how exactly it works and why it's preferred in many cases.

Shell Sort Preview 14:17

Shell sort builds on top of insertion sort, it improves the complexity of it's running time by partitioning the list in a clever way.

Merge Sort Preview 19:23

This belongs to a class of algorithms which uses divide and conquer to break the problem set into smaller pieces. This also makes a time-space trade off to get a faster running time.

Quick Sort Preview 15:30

Quick sort is the sort of choice for developers of programming libraries. Let's see what makes it so attractive.

Binary Search - search quickly through a sorted list Preview 11:10

Binary search is a pretty nifty way to search through a sorted list in O(Log N) time. It's also an interview favorite so make sure you understand it well!

What is recursion - why is it so hard? Preview 16:59

Recursion is pretty hard at the beginning. Let's look at an example of reversing a string and see how we can use recursion to solve the problem. Visualize the input and every step and see how the magic of recursion works.

Binary search - implemented recursively Preview 13:21

We've already seen and understood binary search. This is a perfect first problem to tackle using recursion. Make sure you try it yourself first before seeing the solutions in the class.

Find all subsets of a set Preview 14:55

A classic problem which can be solved recursively. Try out a few smaller sets and see how their subsets look to find patterns.

Check whether 2 binary trees are the same Preview 14:51

Binary trees lend themselves to problems which have really beautiful recursive solutions. The problem may seem hard but the solutions end up being simple. Checking for whether 2 trees are the same is one such problem.

Implement paint fill to color a region on screen Preview 11:01

Paint fill allows you to color regions on screen while using drawing software. Implement a recursive solution to paint fill a region on the display screen.

Build A car Given Tasks And Dependencies Preview 14:17

Say you were given all the tasks needed to build a complete car. These tasks may depend on one another. Set up a data structure to represent a task and it's dependencies and write code to build a car.

Generate Anagrams Of A Word Preview 16:34

An anagram of a word is simply a word with the letters of the original word rearranged. This is complicated but lends itself well to a recursive solution.

Help A Rat Find It's Way Through a Maze Preview 13:01

There can be several paths out of a maze. Help a rat placed anywhere in maze to find it's way out.

Place 8 Queens On A Board Safely Preview 17:50

Another classic problem with an elegant recursive solution.

Meet The Stack - Simple But Powerful Preview 15:40

The stack is a very simple and easy to understand data structure. However it lies underneath many complicated real world problems and is incredibly useful.

Building A Stack Using Java Preview 16:53

Let's build a stack for real using Java. It'll have all the operations we're interested in - push, pop, peek, size etc. It can hold any data type, it's a generic class.

Match Parenthesis To Check A Well Formed Expression Preview 11:21

Problems which use stacks as a part of their solutions are very common in programming interviews. Matching parenthesis to check for well formed expressions is a classic interview question - let's solve this using the stack we're already implemented.

Find The Minimum Element In A Stack In Constant Time Preview 08:51

Another interview question implemented. You have space available but your processing needs to be very fast indeed. How would you keep track of the minimum element of a stack as it changes?

Meet The Queue - A Familiar Sight In Everyday Life Preview 14:11

The queue belongs to the same linear data structure family as the stack but it's behavior is very different. Queues are much more intuitive as there are plenty of real world examples where a queue is the fair and correct way of processing.

The Circular Queue - Tricky But Fast Preview 19:44

A common, fast but slightly tricky implementation of the queue is the array where the last element wraps around to the first. An interview favorite, let's see how to implement the circular queue.

Build A Queue With Two Stacks Preview 17:30

We know the stack, and we know the queue. This problem brings them together. It's possible to mimic the behavior of a queue using 2 stacks in the underlying implementation. Let's write the most efficient code possible to make this work.

Meet The Binary Tree - A Hierarchical Data Structure Preview 13:03

The binary tree is an incredibly useful hierarchical data structure. Many other, more complex data structures, use the binary tree as the foundation. Let's see what a binary tree looks like and learn some simple terminology associated with the tree.

Breadth First Traversal Preview 18:43

Traversing a binary tree can be done in variety of ways. The breadth first traversal visits and processes nodes at every level before moving on to the next. Let's visualize breadth first traversal and see how it's implemented.

Depth First - Pre-OrderTraversal Preview 14:35

Depth first traversal can be of 3 types based on the order in which the node is processed relative to it's left and right sub-trees. Pre-order traversal processes the node before processing the left and then the right sub trees.

Depth First - In-Order and Post-Order Traversal Preview 13:51

Depth first traversal can be of 3 types based on the order in which the node is processed relative to it's left and right sub-trees.

In-order traversal processes the left subtree, then the node itself and then it's right sub trees. Post-order traversal processes the node *after* it's left and right subtrees.

The algorithms are all remarkably similar and very easy once you use recursion.

The Binary Search Tree - an introduction Preview 09:49

A Binary Search Tree is a binary tree with specific constraints which make it very useful in certain operations. Learn what a BST is and how we can use it

Insertion and Lookup in a Binary Search Tree Preview 17:00

Insertion and Lookup are operations which are very fast in a Binary Search Tree. See how they work and understand their performance and complexity.

Minimum Value, Maximum Depth And Mirror Preview 12:14

Find the minimum value in a binary search tree, find the maximum depth of a binary tree and mirror a binary tree. Learn to solve these problems recursively and see implementation details.

Count Trees, Print Range and Is BST Preview 14:38

Count the number of structurally unique binary trees that can be built with N nodes, print the nodes within a certain range in a binary search tree and check whether a certain binary tree is a binary *search* tree. Learn to solve these problems and understand the implementation details.

Has Path Sum, Print Paths, Least Common Ancestor Preview 14:49

Check if a path from root node to leaf node has a specified sum, print all paths from the root node to all leaf nodes and find the least common ancestor for two nodes in a binary tree. Learn to solve these problems and understand the implementation details.

The Heap Is Just The Best Way to Implement a Priority Queue Preview 17:15

Priority Queues allow us to make decisions about which task or job has the highest priority and has to be processed first. Common operations on a Priority Queue are insertion, accessing the highest priority element and removing the highest priority element.

The Binary Heap is the best implementation of the Priority Queue.

Meet The Binary Heap - It's A Tree At Heart Preview 12:39

The Binary Heap is logically a Binary Tree with specific constraints. Constraints exist on the value of a node with respect to it's children and on the shape of the tree. The heap property and the shape property determine whether a Binary Tree is really a Heap.

The Binary Heap - Logically A Tree Really An Array Preview 17:13

The Binary Heap may logically be a tree, however the most efficient way to implement it is using an array. Real pointers from parent to child and from child to parent become implicit relationships on the indices of the array.

The Binary Heap - Making It Real With Code Preview 07:38

Let's build a real heap in Java!

Heapify! Preview 19:32

How do we ensure that when we add an element or remove an element from an existing heap, that the heap property and shape property is maintained? This operation is called Heapify.

Insert And Remove From A Heap Preview 16:34

Once we understand heapify, adding and removing elements from a heap become very simple.

Heap Sort Phase I - Heapify Preview 19:31

Back to sorting. The Heap Sort uses a heap to transform an unsorted array into a sorted array. Phase I is converting the unsorted array into a heap.

Heap Sort Phase II - The Actual Sort Preview 17:42

Phase II actually outputs the final sorted array. It involves removing the elements from the heap and placing it in a sorted array. The cool thing is that all of this can be done in-place.

Maximum Element In A Minimum Heap and K Largest Elements In A Stream Preview 15:54

Let's practice heap problems! Use the heap property to find the largest element in a minimum heap and the K largest elements in a stream.

Merge K Sorted Lists Into One Sorted List Using A Heap Preview 11:40

An interview favorite - the streaming median! This uses heaps in a very interesting and elegant way.

Find The Median In A Stream Of Elements Preview 16:04

Starting with K sorted lists, get one complete sorted list which includes all the elements from the original K lists. This is easy and efficient when done using heaps.

Introducing The Graph Preview 15:40

The graph is a data structure that is used to model a very large number of real world problems. It's also an programming interview favorite. The study of graphs and algorithms associated with graphs forms an entire field of study called graph theory.

Types Of Graphs Preview 07:21

Edges in a graph can be directed or undirected. A graph with directed edges forms a Directed Graph and those with undirected edges forms an Undirected Graph. These edges can be likened to one-way and two-way streets.

The Directed And Undirected Graph Preview 14:29

Different relationships can be modeled using either Directed or Undirected graphs. When a graph has no cycles it's called an acyclic graph. A graph with no cycles is basically a tree.

Representing A Graph In Code Preview 08:09

There are a number of different ways in which graphs can be implemented. However they all follow they same basic graph interface. The graph interface allows building up a graph by adding edges and traversing a graph by giving access to all adjacent vertices of any vertex.

Graph Using An Adjacency Matrix Preview 15:25

An adjacency matrix is one way in which a graph can be represented. The graph vertices are rows and columns of the matrix and the cell value shows the relationship between the vertices of a graph.

Graph Using An Adjacency List And Adjacency Set Preview 17:53

The adjacency list and the adjacency set are alternate ways to represent a graph. Here the connection between the vertices is represented using either a linked list or a set.

Comparison Of Graph Representations Preview 10:08

Compare the adjacency matrix, adjacency list and the adjacency set in terms of space and time complexity of common operations

Graph Traversal - Depth First And Breadth First Preview 14:56

Common traversal methods of trees apply to graphs as well. There is an additional wrinkle with graphs, dealing with cycles and with unconnected graphs. Otherwise the algorithms are exactly the same as those we use to traverse trees.

Topological Sort In A Graph Preview 17:30

Topological sort is an ordering of vertices in a graph where a vertex comes before every other vertex to which it has outgoing edges? A mouthful? This lecture will make things easy to follow. Topological sort is widely used in real world problems.

Implementation Of Topological Sort Preview 06:56

Here is the code in Java to implement topological sort.

Design A Course Schedule Considering Pre-reqs For Courses Preview 13:01

Given a course list and pre-reqs for every course design a course schedule so pre-reqs are done before the courses.